to bind or oblige morally or legally

to obligate oneself to purchase a building.

to pledge, commit, or bind (funds, property, etc.) to meet an obligation.

morally or legally bound; obliged; constrained.

necessary; essential.

Biology . restricted to a particular condition of life, as certain organisms that can survive only in the absence of oxygen

obligate anaerobe opposed to facultative

adjective

bounden , called by duty , committed , compelled , contracted , duty-bound , enslaved , forced , indebted , indentured , obliged , pledged , required , tied , under obligation , urged , beholden , bound