Words formed from the letters of other words (8)
I believe the answer is:
anagrams
(Other definitions for anagrams that I've seen before include "Words with letters transposed to form other words" , "Words turned into other words" , ""Sword" from "words" and "seraph" from "phrase", for example" , "Mixed-up words as ragman have it" , "Words formed from letters of other words" .)