To display a subtle emotional reaction, such as consternation, annoyance, sadness, joy, etc. Generally used in the negative to denote that the person in question did not display even a hint of an emotional response.
Mary didn’t even bat an eye when I told her I was moving out.
That guy is dangerous. I heard he killed a man without batting an eye.
not bat an eyelid
informal Show (or showing) no surprise or concern.
she fell down and grazed her knees, but she didn’t bat an eyelid
Example sentences
not bat an eye (or eyelash)
informal Show (or showing) no surprise or concern.
he read it without batting an eyelash