Boyd’s Bible Dictionary:

(collected together). Biblically, the Hebrew nationality (Num. 15:15). Generally, collected Jewry (Ex. 12:19). A popular assembly (Acts 19:32,39,41). A religious assembly, or church (Acts 7:38).

Concise Bible Dictionary:

The term is constantly applied in the Old Testament to the community of Israel, and also to the actual assembling together of the people according to the unity of the congregation. Every descendant of the twelve tribes formed a part of that community. Those of other nations were received into the congregation on becoming PROSELYTES. The Ammonite and the Moabite were forbidden ever to come into the congregation of Jehovah, and there were a few other restrictions (Deut. 23:1-4). For various offenses an Israelite was cut off from the congregation (Exod. 12:19; Num. 9:13). See EXCOMMUNICATION.