a concussion, or blow, made by water in striking, as against the sides of a pipe or vessel containing it.
2. water hammer ·add. ·- a metal hammer used when heated, as by dipping in hot water, to blister the skin, as for counterritation.
3. water hammer ·- a vessel partly filled with water, exhausted of air, and hermetically sealed. when reversed or shaken, the water being unimpeded by air, strikes the sides in solid mass with a sound like that of a hammer.