A word’s part of speech is the class it belongs to that tells us how to use the word in a sentence. If you can tell that “I baked a cake” is good English while “I baked a delicious” is bad, you’re already used to making decisions based on parts of speech.
There are eight parts of speech in English: noun, verb, adjective, adverb, pronoun, preposition, conjunction, and interjection. (Some count the article, a special kind of adjective, as a ninth.)
Noun
A noun is a name. The word noun itself is the French version, brought to English, of the Latin word nōmen, which meant ‘name’. Nouns are called that because they name things: people, places, objects, and ideas.
Nouns can be divided in several ways. One is whether the noun is common or proper. A common noun is a name common to a whole class of things, like bear or park. A proper noun is a name proper, or specific, to one thing, like Smokey or Yellowstone.
Another division is between concrete and abstract. A concrete noun names a thing you can perceive by your senses: a table, a melody, the ocean. An abstract noun names a thing you can know only in your mind: friendship, loneliness, capitalism.
A third division is between count nouns and mass nouns. Count nouns name things that can be counted as units: a tree, two dogs, three houses. Mass nouns name things that can’t be counted as discrete units but can be considered only as a mass: air, flour, intelligence. Most native speakers don’t think much of, or even notice, the difference between count and mass nouns; but ignorance of it can cause errors in article usage and subject–verb agreement, errors made often by foreign learners of English.
Verb
A verb is what a noun does. It names an action or state of being.
Like nouns, verbs can be divided in several ways. The main division is between action verbs and linking verbs. An action verb names an action: run, jump, swim. A linking verb links one noun (the subject of the sentence) to another noun or an adjective (the complement). The most common linking verb is be (and its many forms: is, are, was, were, been), as in “A bear is an animal” and “Elephants are large.” While be is often a linking verb, it can also be an action verb (“There is some chicken in the fridge”) or a helping verb (“My friend is eating ramen,” “The ramen is eaten by my friend”).
Verbs can also be classed as transitive or intransitive. A transitive verb takes a direct object, while an intransitive verb does not. Most English verbs can be either, but some can be only one or the other. English has three pairs of these verbs: raise (trans.) vs. rise (intrans.), set (trans.) vs. sit (intrans.), and lay (trans.) vs. lie (intrans.). Because most verbs can be either, many English speakers misuse the ones that can’t – especially lay/lie. If you care about using them correctly, you can’t go by what you hear; you have to check whether there’s a direct object. Beyond transitive and intransitive, a few verbs are ditransitive, taking both a direct and an indirect object: give, make, feed.
Another division between verbs is strong vs. weak. A strong verb forms its past tense and/or past participle by changing the vowel in the middle: sing–sang–sung, ring–rang–rung, throw–threw–thrown. A weak verb forms both its past tense and past participle by adding -ed: walk–walked–walked, jump–jumped–jumped. The idea is that weak verbs must lean on the suffix like a cane. Most verbs were strong in Old English, but because new and borrowed verbs are weak by default, most verbs in Modern English are weak.
At the sentence level, an important distinction is between finite and nonfinite verbs. A finite verb is one joined to a subject and limited to match that subject. Finite verbs are specified for six features: person, number, tense, aspect, voice, and mood. Nonfinite verbs are not joined to a subject and thus have no person, number, tense, or mood, though they do have aspect and voice.
English verbs can pile up into phrases: “I eat” can become “I am eating,” “I have eaten,” “I will have eaten,” or even “I will have been eating.” In this kind of phrase, only the first verb is finite; the rest are nonfinite. The verb at the end, the main verb, names the action; the verbs at the beginning are helping verbs that change the aspect, voice, or mood.
A helping verb that changes the mood is called a modal: can/could, may/might, will/would, shall/should, must, ought. Unlike most verbs, modals can’t be made nonfinite, and so must come at the front of their phrases. That’s why “used to could” doesn’t work.
Adjectives
An adjective describes or limits a noun. In Latin, ad means ‘at’ and ject means ‘throw’, so an adjective is a word you throw at a noun. Examples are blue, small, happy, and beautiful.
An adjective can simply assign a trait to a noun (“Elephants are large”), or it can assign more of the trait to one noun than to others (“African elephants are larger than Asian ones,” “The elephant is the largest land animal”). This difference is called degree. Large is the positive degree, larger is the comparative degree, and largest is the superlative degree. Most nouns two syllables or shorter form the comparative with -er and the superlative with -est, while most nouns three syllables or longer form the comparative with more and the superlative with most; but there are exceptions, like staid and fun. Many of the exceptions are not originally adjectives: staid comes from the verb stay, and fun was first a noun.
Often ranked among the adjectives is the article: a(n) and the. The Latin word articulum means “little joint”; by marking noun phrases, articles visibly divide a sentence into phrases, just as your elbow divides your arm. A(n) is the indefinite article, used with nouns that haven’t been clearly specified for the listener or reader: “a cat” could be any cat, not necessarily that cat over there. The is the definite article, used with nouns that either have been clearly specified or don’t need to be because there’s only one of them: “the book” is that one that I already mentioned, while “the sun” needs no introduction because it’s unique in our sky. Historically, a(n) derives from one and the from that, which makes sense if you think about it.
In general, European languages – English, French, Spanish, and German – have articles, while other languages – Korean, Japanese, Chinese – don’t. If your native language doesn’t have them, you’re probably going to have a hard time using them in a language that does. Mastering articles as a foreign learner is famously hard, but if you’re serious about doing it, you’ll want to know that it involves three features of the noun: definiteness, number, and countability. If a noun is definite, it takes the. If it’s indefinite and plural, it takes no article. If it’s singular, it may need a(n): singular count nouns take it, singular mass nouns don’t. Most article errors by foreign learners arise from either (1) an unawareness of whether the noun is count or mass, (2) disregard for the noun’s number, or both.
Adverb
Just as adjectives describe nouns, adverbs describe verbs – but they also describe adjectives and other adverbs. You can run quickly, where quickly describes the verb run. You can also run very quickly, where very describes the adverb quickly. Or you can be an extremely fast runner, where extremely describes the adjective fast. Most people know that adverbs describe verbs but forget that they also describe adjectives and other adverbs.
One easy way to spot an adverb is by the common suffix -ly: quickly, extremely, incredibly. The same suffix, though, can also mark adjectives: a sickly child, a kindly old lady, slovenly speech. -ly is a contraction of -like, which can be an adjective or an adverb: “The warlike tribe pounced wolflike on its enemy.”
Like adjectives, adverbs also have degree: positive, comparative, and superlative. Unlike adjectives, adverbs never form the comparative and superlative with a suffix but always use more and most: “She runs more quickly than he does, but I run most quickly of all.”
The most important adverb, measured by its impact on meaning, is not.
Pronoun
You probably think pro means ‘good’, either good at an activity (like a pro golfer) or doing more good than harm (like pros and cons). That’s true, in a limited way: in the first meaning, pro is short for professional; in the second, pros act for you while cons (short for contrā) act against you). In Latin, prō means ‘forward’ or ‘in front of’, thus ‘in place of’. It is this last meaning we see in pronoun. A pronoun stands in place of a noun.
There are many kinds of pronouns: personal, indefinite, demonstrative, relative, reflexive, and intensive. Further, personal pronouns can be interrogative. Though most English speakers can’t tell any of those apart, knowing how to use them is essential to using English well.
Most errors in pronoun usage, by native and foreign speakers, come not from the abundance of pronoun classes but from a very old feature of personal pronouns that hasn’t been lost yet: case. Case is the form a pronoun takes that tells us what job the pronoun is doing in the sentence. In Old English, nouns and adjectives also used case for the same purpose. There were once four cases: nominative for subjects and subject complements; genitive for possessives; accusative for direct objects, object complements, and objects of some prepositions; and dative for indirect objects and objects of other prepositions. Now there are three: subjective for subjects and subject complements; objective for direct objects, indirect objects, objects of prepositions, and object complements; and possessive. Most people have no trouble using pronoun case most of the time, but there are two mistakes nearly everyone makes: using an object pronoun for a subject complement and using subjective who for objective whom (or, less often, the other way around). Both these errors are so common in speech that they aren’t widely considered wrong – especially since whom is a “zombie word,” completely dead in spoken English and lumbering on only in writing. When you write, you’ll likely want to be able to use the correct case forms.
Preposition
If I asked you to, you could probably give me thirty examples of prepositions: in, on, around, over… But could you tell me what a preposition is? Most people can’t. It’s hard to explain.
Well, here’s what it is: a preposition is a particle that turns a noun into a modifier. A modifier is either an adjective or an adverb. By putting a preposition (at) in front of a noun (restaurant), you can turn that noun into an adjective (“The ramen at this restaurant is spicy”) or adverb (“Let’s eat at this restaurant”). In the first sentence, “at this restaurant” modifies ramen, so it’s an adjective. In the second, “at this restaurant” modifies eat, so it’s an adverb. Either way, “at this restaurant” is a prepositional phrase.
Why is a preposition called that? Pre means ‘before’ and posit means ‘put’, and if you look at a bunch of prepositional phrases you’ll notice that the preposition is always put before the noun: in the kitchen of the restaurant down the street.
Some people consider it incorrect to end a clause with a preposition: “Which team are you rooting for?” This clause-ending preposition is called a dangling preposition. In grammar, “dangling” means misplaced. Dangling preposition–haters point to the pre in the word and to languages like Latin and Spanish, whose prepositions can’t be dangled. But dangling prepositions in English (speech and writing) has been common practice for a long time, and it’s often better style than not dangling (“For which team are you rooting?”). When people do choose not to dangle in dangle-friendly sentence patterns like questions and adjective clauses, they come off sounding stiff and formal. There are times you’ll want to do that – but when you’d rather sound more natural, casual, and friendly, dangling is more appropriate. Just know how to avoid dangling when you take a multiple-choice test like the SAT.
Conjunction
From Latin con- ‘together’ + junct ‘join’, conjunctions are glue words. They hold other words, phrases, and clauses together.
Just about everyone can name and and but as conjunctions, but there are actually two main kinds of conjunctions you need to know: coordinating and subordinating.
Coordinating conjunctions (co- ‘same’ + ord ‘rank’) join two words, phrases, or clauses of equal rank: “My brother and I ordered sushi.” I’m no more important than my brother, and he’s no more important than I; we’re equal participants in the order. A coordinating conjunction can also join predicates that share a subject: “I ate my dinner and went to bed.” Note that no comma is needed before the conjunction that links two predicates. But when the conjunction links two independent clauses, you do need the comma: “I went hungry, for there was no food in the house.” Kids often put in the needless comma between predicates and forget the needed one between clauses. There are seven coordinating conjunctions, easily memorized by the acronym FANBOYS: for, and, nor, but, or, yet, so.
Subordinating conjunctions (sub ‘lower’ + ord ‘rank’) push down the word, phrase, or clause they introduce, taking it out of the main clause and shoving it lower. These conjunctions commonly introduce adverb clauses (“I ate because I was hungry”) and noun clauses (“He saw that I was hungry”), though they do sometimes introduce single words (“My cooking, while not superb, is enough to sustain me”). Some subordinating conjunctions: because, since, before, after, while, though, although.
There is a third kind of conjunction called correlative. These conjunctions come in pairs: both … and, either … or, neither … nor, not only … but also. Strictly speaking, a “correlative conjunction” is not a single or pure conjunction, but a mashup of two conjunctions (both … and) or of conjunctions and adverbs (not only … but also). As a species of conjunction, correlatives are nice to be aware of, but not as important as coordinating and subordinating conjunctions.
Interjection
Wow, where the heck do I begin? Wow and heck, while enriching the meaning of that sentence, added nothing to it grammatically. They’re un-words, words I just tossed in between the real words. In fact, that’s what interjection means: inter ‘between’ + ject ‘throw’. (Remember ject from adjective?)
Interjections can be single words (wow) or whole phrases (oh my gosh). Either way, they often start as other parts of speech and, gradually bleached of grammatical meaning, devolve into interjections. They are often swear words, or euphemisms for swear words: heck softens/sidesteps hell, and gosh respectfully avoids taking God’s name in vain. Both hell and God are nouns, which is why we can put the in front of heck and my in front of gosh.
It’s not just English; every language has interjections.