What It Scores
HAJJ is a valid word in the tournament list this site uses. Tile values only, before any premium square: 21 in Scrabble and 25 in Words With Friends. The letters break down as H4 A1 J8 J8.
Words Made From The Letters In HAJJ
4 shorter words come out of these tiles. On a board that matters more than the long play, because a short word on a premium square often beats a long one on plain squares.
3 letter words (1)
2 letter words (3)
Longer Words Containing HAJJ
HAJJ appears inside each of these, which is what makes it worth knowing as a hook.
Next: the Word Unscrambler for any letters at all. Full entry and definition at Merriam-Webster.