congregationyoudaoicibaDictYouDict[congregation 词源字典]
congregation: [14] Etymologically, a church’s congregation is comparable to a pastor’s flock. The word comes from Latin congregātiō, a noun derivative of congregāre ‘flock together’. This was a compound verb formed from the collective prefix com- and grex ‘flock, herd’ (source of English egregious and gregarious). Congregation was thus originally simply a ‘meeting, assembly’; its religious connotations arose from its frequent use in the 1611 translation of the Bible to render ‘solemn public assembly’. The verb congregate was independently borrowed in the 15th century.
=> aggregate, egregious, gregarious, segregate[congregation etymology, congregation origin, 英语词源]
congregation (n.)youdaoicibaDictYouDict
mid-14c., "a gathering, assembly," from Old French congregacion (12c., Modern French congrégation), from Latin congregationem (nominative congregatio), noun of action from congregare (see congregate).

Used by Tyndale to translate Greek ekklesia in New Testament and by some Old Testament translators in place of synagoge. (Vulgate uses a variety of words in these cases, including congregatio but also ecclesia, vulgus, synagoga, populus.) Protestant reformers in 16c. used it in place of church; hence the word's main modern sense of "local society of believers" (1520s).