Catholicism (n.)

mid-14c., "of the doctrines of the ancient Church" (before the East/West schism), literally "universally accepted," from French catholique, from Church Latin catholicus "universal, general," from Greek katholikos, from phrase kath' holou "on the whole, in general," from kata "about" + genitive of holos "whole" (from PIE root *sol- "whole, well-kept").

Medieval Latin catholicus was practically synonymous with Christianus and meant "constituting or conforming to the church, its faith and organization" (as opposed to local sects or heresies). With capital C-, it was applied by Protestants to the Church in Rome by c. 1554, after the Reformation began in England. The general sense of "embracing all, universal" in English is from 1550s. The meaning "not narrow-minded or bigoted" is from 1580s. The Latin word was rendered in Old English as eallgeleaflic.

word-forming element making nouns implying a practice, system, doctrine, etc., from French -isme or directly from Latin -isma, -ismus (source also of Italian, Spanish -ismo, Dutch, German -ismus), from Greek -ismos, noun ending signifying the practice or teaching of a thing, from the stem of verbs in -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached. For distinction of use, see -ity. The related Greek suffix -isma(t)- affects some forms.