The Greek ekklesia (ek-klay-SEE-ah) means an assembly. As in Acts 19:40, it is not necessarily a religious word at all.
Often it is explained as meaning "the called out." While this may have been originally true (etymologically), it is doubtful the word should be allowed to carry that much freight. It is a common word, and applies to any number of public meetings.
Forms of ekklesia appear over 100 times in the N.T. In most instances the term refers to the Christian community,