Definition of «to bat an eye»

The phrase "to bat an eye" means to not show any surprise, concern, or hesitation in response to something unusual or shocking.

A fact I really didn't bat an eye at until I hosted a dinner party a few weeks back. (delishknowledge.com)
Apparently, Swedish mothers don't bat an eye at taking their children out in the cold. (mommyish.com)
My kids no longer even bat an eye when I break out into a dance. (homestoriesatoz.com)
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