| Hydra | small tubular solitary freshwater hydrozoan polyp |
|---|---|
| Hydra | a long faint constellation in the southern hemisphere near the equator stretching between Virgo and Cancer |
| Hydra | (Greek mythology) monster with nine heads |
| Hydra | an antihypertensive drug (trade name Apresoline) that dilates blood vessels |
| Hydra | an abnormality of pregnancy |
| Hydra | any of various deciduous or evergreen shrubs of the genus Hydrangea |
| Hydra | deciduous climber with aerial roots having white to creamy flowers in fairly flat heads |
| Hydra | deciduous shrub with creamy white flower clusters |
| Hydra | sometimes included in the family Saxifragaceae |
| Hydra | deciduous shrub bearing round-headed flower clusters opening green and aging to pink or blue |
| Hydra | deciduous shrub or small tree with pyramidal flower clusters |
| Hydra | deciduous climber with aerial roots having large flat flower heads |