to obligate or bind (oneself or somebody else) to a course of action or a set of beliefs

a committed Christian

to assign (somebody or something) to some particular course or use

All available troops were committed to the attack

(usu + to) to entrust (something or somebody) to somebody's care

to place (somebody) in a prison or psychiatric hospital

to transfer or consign (something) to a place or a process

He refused to commit anything to paper

to refer (e.g. a legislative bill) to a committee