congregation (n.) Look up congregation at
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).