wince 
(wĭns)
(wĭns)intr.v. winced, winc·ing, winc·es
To shrink or start involuntarily, as in pain or distress; flinch.
n.
A shrinking or startled movement or gesture.
[Middle English wincen, to kick, from Old North French *wencier, variant of Old French guencir, of Germanic origin.]
wincer n.