What is a metaphor in poems?

A metaphor is a phrase comparing two things without using "like" or "as."

Ex. Mimi is a butterfly: free, loose, and beautiful!

The example is saying (without saying "Mimi is like a butterfly") that Mimi is free, loose and beautiful, JUST LIKE A BUTTERFLY.

A metaphor is a figure of speech where one phrase is used in place of another. For example, "porcelain palace" used in place of "bathroom" or "go-go juice" for "gasoline."