verb trans
to return (something) to a straight position
to unfasten (e.g. a sail) from a spar or stay
to cast loose or untie (e.g. a rope)
to become more relaxed, informal, or outgoing in manner
Then the great man unbent. His face beamed — Samuel Butler
Mrs Saunders so far unbent as to remark to Mrs Crick that the evening had been a fine one — Saki
to become straight