For example, Without my glasses I'm blind as a bat, or I had no idea they wanted me to take over his job; I was blind as a bat. People figured bats were blind and they were right. The phrase ‘As Blind as a Bat’ refers to someone who is unwilling to recognize bad things, or someone who is completely blind. Definitions by the largest Idiom Dictionary. What is the origin of the idiom as blind as a bat? What does blind as a bat expression mean? When people saw bats fly into walls and/or narrowly miss them. What … Example of Use: “Will is so in love, he is as blind as a bat when it comes to Kate’s rude behavior.” Although the bat is known not to come out into the light, a bat can't detect light because a bat is blind and uses a sense called sonar to find its way around. They, like many animals, are born blind, but gain sight within their first seven to nine days. Quite blind; also, unaware. Definition of blind as a bat in the Idioms Dictionary. The saying "blind as a bat" probably arose because of the way bats fly around, darting here and there at night. You can use the idiom ‘As Blind as a Bat’ to describe someone who refuses to notice an obvious thing. Bats are not blind for their entire lives. blind as a bat. blind as a bat phrase.