seagoing I. \ˈ ̷ ̷ˌ ̷ ̷ ̷ ̷\noun : travel by sea : seafaring II. adjective 1. a.: designed or adapted for sailing the open sea in distinction from rivers or harbors < a seagoing tug > b.: fitted to be used on a seagoing vessel < a seagoing chronometer > 2. a.: seafaring b.: catadromous