What It Scores
UM is a valid word in the tournament list this site uses. Tile values only, before any premium square: 4 in Scrabble and 5 in Words With Friends. The letters break down as U1 M3.
Anagrams of UM (1)
Same letters, different order. Any of these plays the same tiles for the same score.
Longer Words Containing UM
UM appears inside each of these, which is what makes it worth knowing as a hook.
ABOMASUMACCUMBENCYACCUMBENTACCUMULATEACETABULUMACETUMACHAENIUMACHAENIUMSACHENIUMACHENIUMSACICULUMACICULUMSACONITUMACONITUMSACROTERIUMACTINIUMACTINIUMSACUMENACUMENSACUMINATEACUMINATEDACUMINATESACUMINOUSADDENDUMADDENDUMSADSUMADUMBRALADUMBRATEADUMBRATEDADUMBRATESADYTUMAECIDIUMAECIUMAEROBIUMAGENDUMAGENDUMSAGERATUMAGERATUMSALARUMALARUMED
Next: the Word Unscrambler for any letters at all, and the two and three letter lists. Full entry and definition at Merriam-Webster.