A diuretic in pill form.

(chiefly Canada, US) Any of various hard oaks that grow near rivers or swamps, especially Quercus nigra, of the southern US.

On duty as a guard or lookout / Vigilant; alert.

The medical condition of hydrocephalus.

A bottle used for carrying water or other drinks.

Alternative form of keep one's head above water

(idiomatic, intransitive) To guard; to watch over someone or something.

plural of large-headed water snake

Natrix megalocephala, a species of snake in the Colubridae family

(chemistry) Water containing tritium instead of normal hydrogen (symbol T₂O).