1640s, "pertaining to or being a center," also "being that from which other related things proceed," from French central or directly from Latin centralis "pertaining to a center," from centrum (see center (n.)). Centrally is attested perhaps as early as early 15c., which might imply a usage of central earlier than the attested date.
Slightly older is centric (1580s). As a U.S. colloquial noun for "central telephone exchange," first recorded 1889 (hence, "Hello, Central?"). Central processing unit attested from 1961. Central America is attested from 1826.
word-forming element making abstract nouns from adjectives and meaning "condition or quality of being ______," from Middle English -ite, from Old French -ete (Modern French -ité) and directly from Latin -itatem (nominative -itas), suffix denoting state or condition, composed of -i- (from the stem or else a connective) + the common abstract suffix -tas (see -ty (2)).
Roughly, the word in -ity usually means the quality of being what the adjective describes, or concretely an instance of the quality, or collectively all the instances; & the word in -ism means the disposition, or collectively all those who feel it. [Fowler]