| HYD | a drug (trade names Atarax and Vistaril) used as a tranquilizer to treat anxiety and motion sickness |
|---|---|
| HYD | a drug (trade names Atarax and Vistaril) used as a tranquilizer to treat anxiety and motion sickness |
| HYD | coelenterates typically having alternation of generations |
| HYD | colonial coelenterates having the polyp phase dominant |
| HYD | a constellation in the southern hemisphere near the south celestial pole |