To surrender (someone or something)
To admit defeat, capitulate
Become fully taken over by a certain quality, activity, trait, &c.
To abandon (someone or something)
To relinquish (something)
To execute a trade on behalf of another broker.
To stop or quit (an activity, etc.)
To lose hope concerning (someone or something)
To be indebted to someone.
To constrain someone by force or by social, moral or legal means.
To do (someone) a service or favour (hence, originally, creating an obligation).