To constrain someone by force or by social, moral or legal means.
To be indebted to someone.
To do (someone) a service or favour (hence, originally, creating an obligation).
To rebel, particularly against authority.
To turn away; to abandon or reject something; specifically, to turn away, or shrink, with abhorrence.
To cause to turn back; to roll or drive back; to put to flight.
To be disgusted, shocked, or grossly offended; hence, to feel nausea; used with at.
To repel greatly.
An act of revolt.