Noah Webster's New International Dictionary of the English Language

1. (n.) The act of associating, or state of being associated; union; connection, whether of persons of things.

2. (n.) Mental connection, or that which is mentally linked or associated with a thing.

3. (n.) Union of persons in a company or society for some particular purpose; as, the American Association for the Advancement of Science; a benevolent association. Specifically, as among the Congregationalists, a society, consisting of a number of ministers, generally the pastors of neighboring churches, united for promoting the interests of religion and the harmony of the churches.