Webster's Revised Unabridged Dictionary · 1913

Unbend

Unbend (un*bend") , transitive verb

[1st pref. un- + bend.]

1.
To free from flexure; to make, or allow to become, straight; to loosen; as, to unbend a bow.
2.
A remit from a strain or from exertion; to set at ease for a time; to relax; as, to unbend the mind from study or care.
You do unbend your noble strength. — Shakespeare
3.
(a) (Nautical) To unfasten, as sails, from the spars or stays to which they are attached for use.
(b)
(Nautical) To cast loose or untie, as a rope.

Unbend , intransitive verb

1.
To cease to be bent; to become straight or relaxed.
2.
To relax in exertion, attention, severity, or the like; hence, to indulge in mirth or amusement.