Obligate
Part of speech: adjective
Definition: Able to exist or survive only in a particular environment or by assuming a particular role: an obligate parasite; an obligate anaerobe. Absolutely indispensable; essential.
Part of speech: verb
Definition: To bind, compel, or constrain by a social, legal, or moral tie. See Synonyms at force. To cause to be grateful or indebted; to oblige. To commit (money, for example) in order to fulfill an obligation.
Compel
Part of speech: verb
Definition: To drive together, round upTo overpower; to subdueTo force, constrain or coerceTo exact, extort, (make) produce by force
Example sentence: Honesty compels me to say that I am not a socialist. But so what?