a poem that does not have a set rhyme scheme or set meter
A free verse poem is just that, a poem that is free. It is free of all rules or constraints. It does not have a set rhyme scheme or set meter. Rhyme scheme is the pattern in which rhymes line. For example, Shakespeare's sonnets have a particular rhyme scheme labeled ABAB CDCD EFEF GG. Meter is the pattern of stressed and unstressed syllables in a poem that creates a rhythm.
Blank verse is a poem that has a specific meter but no rhyme scheme.