ity

ity is a productive derivational suffix in English used to form abstract nouns from adjectives and, less often, from other parts of speech. Nouns created with -ity typically denote a state, condition, or quality of the root, as in clarity (the quality of being clear), reliability (the quality of being reliable), or curiosity (the state of being curious).

Etymology and form: The suffix -ity comes from Latin -itas, via Old French -ité, and arrived in English through the broader Latin and French tradition of word formation. It is one of several suffixes that yield abstract nouns, along with -ness, -ment, -tion, and -hood. In English, -ity attaches to many adjectives by adding the ending to the base form; some related words from the same Latin family reflect historical spellings such as -ety (society) or -ty (quality), which are not always productive suffixes in modern English but share the same origin.

Usage and notes: -ity nouns are common in formal, technical, and academic language, where they name properties, states, or conditions. They can shift meaning subtly depending on the base word, and some adjectives yield irregular or less natural -ity nouns. While highly productive, the suffix is not universal; editors should be aware of exceptions and related forms that come from different historical routes.

See also: related abstract-noun suffixes (-ness, -ment, -tion) and cognate forms in Romance languages (for example, French -ité).