What It Scores
KAY is a valid word in the tournament list this site uses. Tile values only, before any premium square: 10 in Scrabble and 10 in Words With Friends. The letters break down as K5 A1 Y4.
Anagrams of KAY (1)
Same letters, different order. Any of these plays the same tiles for the same score.
Words Made From The Letters In KAY
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.
2 letter words (4)
Longer Words Containing KAY
KAY appears inside each of these, which is what makes it worth knowing as a hook.
Next: the Word Unscrambler for any letters at all, and the two and three letter lists. Full entry and definition at Merriam-Webster.