noun - The periodic rise and fall of the waters of the ocean and its inlets, produced by the attraction of the moon and sun, and occurring about every 12 hours. The inflow, outflow, or current of water at any given place resulting from the waves of tides. The race director took the tides into account when he decided to start the race in the early morning. [Origin: bef. 900; ME (n.); OE tīd time, hour; c. D tijd, G Zeit, ON tīth; akin to TIME]. Synonyms: stream, flood tide and current.