accommodation, adjustment, conservation, elaboration, fitting, preservation, recovery, refinement, resurgence, revitalisation, revitalization, revival, revivification.
Your query has returned 78 words, which include anagrams of betterment as well as other shorter words that can be made using the letters included in betterment.
The words in this list can be used in games such as Scrabble, Words with Friends, Wordscapes and other similar games.