tri·weekly I. \(ˈ)trī+\adjective Etymology:tri- + weekly 1.: occurring, appearing, or being made, done, or acted upon three times a week < a triweekly publication > < triweekly train service > 2.: occurring, appearing, or being made, done, or acted upon every three weeks II. noun : a triweekly publication III. adverb : three times a week < a newspaper published triweekly >