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Glossary of Grammar


This is our glossary of terms we use in our articles.

Welcome to our glossary of grammar! Here, you will find definitions for the key grammatical terms used in our articles and resources about academic writing. The glossary will expand as we continue publishing our series of tips. Click on a letter below to jump to that section.



Adjective -- (part of speech) a word that describes or qualifies a noun (such as new or rapid).

Adverb -- (part of speech) a word that describes or qualifies a verb (such as quickly, very, or never). Adverbs frequently end in '-ly,' but not always.

Antecedent -- a noun, phrase, or element of a sentence mentioned earlier to which a pronoun refers.

Apostrophe (') -- (punctuation mark) a symbol that stands in for omitted characters (as in a contraction); marks the possessive form; or, in rare cases, creates a plural form.

Appositive -- a noun or noun phrase placed next to another noun to further identify or clarify it ("Neil Armstrong, the first American to walk on the moon, was born in Ohio").

Article -- a specialized adjective that indicates something definite (the) or indefinite (a or an). Articles can precede other adjectives (e.g., "a popular method").

Attributive noun -- a noun that is placed directly in front of another noun for use as an adjective (e.g., "plane tickets"). Also called a noun adjunct.

Auxiliary verb -- a second verb that adds some new meaning to a standard verb (e.g., emphasis, mood, change in tense). Common auxiliary verbs in English include will, have, do, can, could, and should. Also called helping verbs.


Colon (:) -- (punctuation mark) a symbol used within a sentence to introduce a list or a related clause. For example, "Three foods were available for purchase: bagels, fruit, and muffins."

Comma (,) -- (punctuation mark) a symbol used within a sentence to separate clauses or items in a list or to offset nonrestrictive relative clauses or appositives, among other uses. The comma introduces a break into the sentence, and proper use of commas is critical to the flow of a sentence, and especially one containing complex elements or ideas. Also see serial comma.

Comparative -- the form of an adjective that indicates a relationship between two nouns, usually in combination with the word than. Comparative adjectives often end in '-er' or include the word more ("The sun is brighter than the moon, but the moon is more accessible to humans").

Complement -- a word or set of words that completes the essence of a sentence or phrase. Complements are often found in the predicate of a sentence. In the sentence "The sun is a yellow star," sun is the subject, and yellow star is the complement. A complement can also be just an adjective ("Editing makes me happy").

Compound modifier -- a descriptive phrase that involves multiple words. These modifiers are frequently hyphenated when found before a noun. Examples include "little-known actress," "high-quality samples," and "randomly assigned participants." Note that modifiers that include an adverb are typically not hyphenated, especially if the adverb ends in '-ly.'

Conjunction -- (part of speech) a word that connects two phrases or ideas. Common examples include and, or, and but.

Conjunctive adverb -- an adverb or adverbial phrase that connects two clauses of a sentence. Common examples include however, therefore, as a result, and hence.

Contraction -- a word that represents a shortened form of another word or phrase. Omitted characters are replaced with an apostrophe. Common examples include it's (for "it is" or "it has"), I'm (for "I am"), and can't (for "cannot").

Count noun -- a noun that has a plural form (often created by adding 's'). Examples include study (studies), association (associations), and nucleus (nuclei, an irregular plural form). Also called a countable noun.


Demonstrative pronoun -- a type of pronoun (including this, that, these, and those) that stands in for one or more nouns that are identifiable in the context of the sentence. Demonstrative pronouns indicate the number of the noun that they replace and whether the object is near the speaker (this/these) or at a distance (that/those). The sentence "You decorate those two cakes, and I'll decorate these" ends with a demonstrative pronoun that stands in for "the cakes near me."

Dependent clause -- a portion of a sentence that is not complete on its own and must be linked to another clause to form a grammatically correct sentence.


Eponym -- a type of noun or phrase that is based on a person's name (e.g., einsteinium, Student's t-test, gram-negative).


Gerund -- the present participle form of a verb (the form ending in '-ing') used as a noun, like the word running in the sentence "Running is a great form of exercise."


Helping verb -- see auxiliary verb.

Hyphen (-) -- (punctuation mark) a symbol that joins words that have a combined meaning, as in six-year-old or short-term.


Imperative -- a grammatical mood that uses the stem of a verb to create a command or request, such as "Please provide your name" and "Click here."

Independent clause -- a portion of a sentence that could stand alone as a complete, grammatically correct sentence.

Infinitive -- the root form of a verb that has not been conjugated for number or tense. Infinitives carry the word to at the front; examples include to walk, to analyze, and to submit.

Interjection -- (part of speech) a word or phrase that conveys strong feeling, usually used by itself or as an introduction to a sentence. Interjections are not commonly used in academic writing.


Mass noun -- a noun that is uncountable and therefore has no plural form. Examples include information, research, rain, and furniture. Also called a non-count noun.


Non-count noun -- see mass noun.

Nonrestrictive element -- additional information about a subject or object in a sentence; removal of a nonrestrictive element would not alter the meaning of the rest of the sentence.

Noun -- (part of speech) any concrete or abstract thing, including people, places, objects, characteristics, and ideas.

Noun adjunct -- see attributive noun.


Object -- a noun or pronoun, usually found in the predicate, which is being acted upon or otherwise involved in the completion of the action that a subject is carrying out. In the sentence "Steve ate the entire pizza," pizza is the object.

Oxford comma -- see serial comma.


Parentheses () -- (punctuation mark) symbols used to delimit nonessential material within in a sentence.

Part of speech -- a class of word that is defined by its grammar and usage. Traditionally, English is considered to have eight parts of speech: nouns, pronouns, adjectives, verbs, adverbs, prepositions, conjunctions, and interjections.

Period (.) -- (punctuation mark) a symbol used to end a sentence or an abbreviation.

Person -- a grammatical attribute that relates whether a subject or object is speaking (first person), being spoken to (second person), or being spoken about (third person).

Plural -- the form of a word that conveys the existence of quantity (more than one). Most nouns are made plural by adding '-s' (or '-es' if they end in 'ch,' 'j,' 's,' 'sh,' 'x,' or 'z'). However, there are numerous irregularities in forming plurals in English, so it is advisable to consult a dictionary if the plural form is unknown or unclear. Verbs can also be adjusted for number (e.g., "they eat" instead of "they eats").

Possessive -- a grammatical form that indicates a noun to which another object belongs. In English, the possessive form is created by adding an apostrophe and an 's' (in the majority of cases). An example would be "This is Jane's book." Pronouns are transformed into new possessive pronouns in place of adding 's' (for example, his is the possessive form of he).

Predicate -- the part of a sentence containing the verb and the assertion made about the subject of the sentence or the action carried out by the subject.

Preposition -- (part of speech) a word (such as of, above, or during) that establishes a relationship or context for a noun, verb, or adjective in a sentence by linking it to an object (noun or pronoun). In the sentence "The money is on the table," the word on is a preposition.

Prepositional phrase -- a clause in a sentence that begins with a preposition (such as of, in, or with) and serves as an adjective or adverb. In the sentence "The money on the table belongs to me," the words on the table form a prepositional phrase that modifies money is the prepositional phrase.

Pronoun -- (part of speech) a word (such as I, she, or it) used as a substitute for a noun, especially a person.

Proper noun -- a noun that represents a person's name or an officially designated place or thing (examples include Einstein, Brazil, and Coca-Cola). Proper nouns are capitalized regardless of where they occur in a sentence.

Punctuation -- the use of symbols (such as the comma, colon, semicolon, hyphen, or period) to provide structure and prevent ambiguity in written language.


Relative pronoun -- a class of pronoun that introduces a clause that modifies a noun in the sentence. Common examples include that, which, and who.

Restrictive element -- information that specifies the nature of a subject or object in a sentence; a restrictive element is required for complete understanding of the sentence.


Semicolon (;) -- (punctuation mark) a symbol used within a sentence to join two independent clauses. For example, "Trial results were entered into the database; all records were coded to preserve anonymity."

Sentence -- a set of words that contains a complete statement, question, or exclamation. A sentence will always include a subject and a predicate.

Serial comma -- the name given to the optional comma separating the final two elements in a list in combination with the word and (e.g., "A, B, and C"). Also called the Oxford comma.

Singular -- the form of a word that conveys the existence of only one. The singular form of a noun is its basic form (e.g., without an '-s' on the end). Verbs also have a singular form (e.g., "he eats instead of "he eat").

Subject -- the noun or pronoun that is performing the action in a sentence or clause, also the noun or pronoun that the sentence or clause is describing.

Subordinate clause -- an element of a sentence that is not complete on its own; another term for a dependent clause.

Superlative -- the form of an adjective that indicates a relationship between three or more nouns. Superlative adjectives indicate that one particular noun possesses the most of a certain quality, and they often end in '-est' or include the word most ("Jupiter is the largest planet in the solar system, but Venus is the most reflective to humans").


Verb -- (part of speech) a word that conveys an action or state of being. Verbs are conjugated to reflect differences in timing of the action (changes in tense, e.g., "I walk" and "I walked") and the nature and number of the subject (e.g., "I walk" and "he walks").

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