1. Growing or remaining under water
   - subaqueous, submerged, submersed, underwater 
2. Partially aquatic; living or growing partly on land and partly in water
   "a marginal subaquatic flora"
   - semiaquatic

See also: aquatic

• ourselves
• Ouse
• Ouse River
• ousel
• oust
• ouster
• ousting
• out
• out and away
• out front
• out in
• out loud
• out of
• out of action
• out of bounds
• out of breath
• out of doors
• out of gear
• out of hand
• out of it
• out of keeping
• out of line
• out of nothing
• out of order
• out of place