Inflection is a set of word forms that show different functions or meanings in a sentence. For example, actors is an inflected form of actor. The s added to actor expresses the meaning more than one. But actress is not an inflected form of actor—it is a different word. In English, nouns, pronouns, verbs, adjectives, and adverbs are inflected. English is a lightly inflected language. Spanish has far more inflection, and ancient Greek is heavily inflected.
The set of inflections of a noun is called declension. The written declension of an English noun shows four forms: common case singular (man, boy), common case plural (men, boys), possessive singular (man’s, boy’s) and possessive plural (men’s, boys’).
The set of inflections of a verb is called conjugation. Some verbs have many different forms. In Spanish, for example, for the verb hablar (“to speak”), the possible conjugations include tense (time of the action), number (singular or plural), and formal and informal forms of address. For example, hablo is the conjugation for “I speak,” and the verb can be conjugated as hablé for “I spoke.” For numbers, the plural form of hablo is hablamos, for “we speak.” To address someone familiar or of the same age, “you speak” would be hablas. To address an older person, the verb would be habla.
