/un"deuhr waw"teuhr, -wot"euhr/ , adj.
1. existing or occurring under water.
2. designed to be used under water.
3. located below a ship's waterline.
adv.
4. beneath the water: to travel underwater.
n.
5. the water beneath the surface: cold currents in the underwater.
6. underwaters , the depths, as of a sea, lake, etc.
[ 1620-30; UNDER- + WATER ]