A similie is an expression we use when comparing two things using the words 'like' or 'as'.
Here are some common examples:
"I'm as blind as a bat without my glasses." - I have bad eyesight, so do bats (the flying birds that appears at night).
"My daughter is as quiet as a mouse."
"It was like a library in the stadium today." - It was very quiet, there was no singing or shouting.
Now complete these other well-known idioms: