abuse, annoyance, annoying, disregard, exploitation, harassment, irritation, maltreatment, molestation, neglect, using, vexation, victimisation, victimization.
Your query has returned 933 words, which include anagrams of mistreatment as well as other shorter words that can be made using the letters included in mistreatment.
The words in this list can be used in games such as Scrabble, Words with Friends, Wordscapes and other similar games.