obligate
verb.
force somebody to do something
We compel all students to fill out this form
Synonym: compel, oblige
verb.
commit in order to fulfill an obligation
obligate money
verb.
bind by an obligation; cause to be indebted
He's held by a contract|I'll hold you by your promise
Synonym: bind, hold, oblige
adj.
restricted to a particular condition of life
an obligate anaerobe can survive only in the absence of oxygen
Antonym: facultative