1. The regular coming together of large groups of individuals, generally to discuss a particular subject. A congress will often last several days and have several simultaneous sessions. The length of time between congresses basis. Most international or world congresses are latter type; national congresses are more frequently held annually. usually annual, although some are on a less frequent 2. European term for Conventions. However, in the United States of America, the word *Congress" refers to the meeting of the Senate and House of Representatives.