<MUH-thur bayr>
This is the TRUE definition of mother
bear. Mother
bear is used as an exclamation to show the highest or lowest (depending on the context) possible level for something to achieve. In other words, it represents the epitome of any adjective. All you have to do is use it in a simile or a metaphor (metaphors are much more common). For example, if something is ANGRIER THAN A MOTHER
BEAR, it is not possible to be any angrier than that, period. If it is incredibly cold outside, like absolute zero, then it is COLDER THAN A MOTHER
BEAR. Get it?