From Middle English -ite, from Old French -ite, -ete, -eteit (“-ity”), from Latin -itātem, from -itās, from Proto-Indo-European *-it- (suffix). Cognate with Gothic -𐌹𐌸𐌰 (-iþa, “-th”), Old High German -ida (“-th”), Old English -þo, -þu, -þ (“-th”). More at -th.
- Used to form a noun from an adjective; especially, to form the noun referring to the state, property, or quality of conforming to the adjective's description.
- Used to form other nouns, especially abstract nouns.
- Many nouns formed with -ity are uncountable; those that are countable form their plurals in -ities.
- The addition of -ity to an adjective results in a shift of stress to the antepenultimate syllable; that is, words in -ity are stressed on the last syllable before the -ity, even in cases where this syllable is part of another suffix (as in words in -ability and -icity). Further, this shift typically results in a change in vowel quality; compare, for example, real and reality, where the sound [æ] in the second word is not present in the first. These vowel quality changes are usually consistent with the spelling of both forms — note that the letter <a> in the second word is present in the first — but sometimes spelling changes are seen, as with the suffix -ous, which when it combines with -ity produces the suffix -osity.
- While a final -c is pronounced [k], before -ity it becomes [s]; compare, for example, elastic and elasticity.
- Final -e is dropped before adding this suffix.