to move back or away suddenly or react physically because something frightens, disgusts (= shocks), or upsets you

At the sight of the dead animal, Diana blenched. 见到动物尸体，黛安娜吓得往后退。

to be very unwilling to do something

My sister blenches at the very thought of changing a baby's nappy. 一想到要换婴儿的尿布，我妹妹就很不情愿。