The phrase “not bat an eyelash” is an idiomatic expression that means to not show any surprise, shock, or concern in response to something unexpected or unusual. When someone says that a person didn’t bat an eyelash, it implies that the individual remained calm, composed, or unaffected, even in a situation that might typically provoke a reaction.
For example, if someone tells a dramatic story about a near-miss accident and their friend listens without reacting, you might say, “He didn’t bat an eyelash at the story.” This suggests that the friend was unfazed by the events described.
The expression often highlights a person’s level of composure or indifference in the face of what might be considered alarming or noteworthy. It can also imply a certain level of experience or familiarity with similar situations, leading to a lack of surprise.