There are 54 words hidden in the letters of HARMFUL, from 14 two-letter words up to HARMFUL (7 letters). For points, HARMFUL is best at 15.
No other single word uses all 7 letters of HARMFUL. HARMFUL has 7 letters: 2 vowels and 5 consonants, worth 15 points before any board bonuses.
7-letter words 1
6-letter words 3
armful11fulham14fulmar11
5-letter words 4
haulm10larum7mural7rumal7
4-letter words 16
alum6arum6farl7farm9flam9furl7half10halm9harl7harm9haul7hula7hurl7marl6maul6mura6
3-letter words 16
amu5arf6arm5far6flu6fur6ham8hum8lam5lar3lum5lur3mar5rah6ram5rum5
2-letter words 14
ah5al2am4ar2fa5ha5hm7la2lm4ma4mf7mu4uh5um4
Words are from our open word list and include some game-only words. Rude words are left out of this page; the unscrambler shows every valid word, lets you add blank tiles and filter by length.