Webster's Revised Unabridged Dictionary · 1913

Flinch

Flinch , intransitive verb

[Probably from Old English flecchen to waver, give way, French fléchir, from Latin flectere to bend; but prob. influenced by English blench. Compare Flex.]

1.
To withdraw from any suffering or undertaking, from pain or danger; to fail in doing or preserving; to show signs of yielding or of suffering; to shrink; to wince; as, one of the parties flinched from the combat.
A child, by a constant course of kindness, may be accustomed to bear very rough usage without flinching or complaining. — Locke
2.
(Croquet) To let the foot slip from a ball, when attempting to give a tight croquet.

Flinch , noun

The act of flinching.