Many English teachers talk at length about the importance of "agreement." In the context of grammar, "agreement" refers to the matching of words in number and gender. Although native speakers are more likely to make errors in subject-verb agreement (in which the number of subjects does not match the verb), it is also possible to mismatch a noun with its adjective.

Nouns

A noun is any word that names a person, place, thing or concept. For example, "Queen Elizabeth," "United States of America," "cat" and "happiness" are all nouns.

Nouns can be singular--that is, naming just one person, place, thing or concept--or plural--naming two or more. For example, "teacher," "city," "book" and "idea" are all singular, while "teachers," "cities," "books" and "ideas" are all plural.

Pronouns

A pronoun is a word that takes the place of a noun. For example, "I," "me," "us" "them" and "each" are all pronouns, as are "it," "anyone," "you," "they" and "our."

Adjectives

An adjective is a word that describes or limits a noun or pronoun. For example, in the phrase "interesting book," the word "interesting" is describing "book." In the phrase "that book," the word "that" is limiting the word "book" by telling you which one book is under discussion.

An adjective also might describe or limit a pronoun, as in "She is beautiful" or "You are intelligent."

Noun-Adjective Agreement

An adjective must always "agree" with its noun or pronoun by matching its number. Singular nouns take singular adjectives, while plural nouns take plural adjectives. For example, it would make no sense to say "two book," because "book" is singular while "two" is plural. We instead say "two books." Similarly, the phrase "a blue trees" lacks agreement because "a" indicates just one tree, while "trees" is plural. We must therefore change the phrase either to "a blue tree" or to "the blue trees."

Foreign Languages

In English, the only nouns assigned a gender are the ones having inherently to do with the sexes, such as "man" or "woman," "girl" or "boy." In many other languages, however, nouns are assigned genders. The word for "sun," for example, might be male (as in "The sun is shining brightly today; he is hot.") In that case, the adjectives used to describe the sun must also be in the male "case," to agree with the noun.