Yes, harp is a Scrabble word!
...and is worth 9 points in Scrabble, and 9 points in Words with Friends
harp
Verb
1. Come back to
2. Play the harp
Noun
1. A chordophone that has a triangular frame consisting of a sounding board and a pillar and a curved neck; the strings stretched between the neck and the soundbox are plucked with the fingers
2. A pair of curved vertical supports for a lampshade
3. A small rectangular free-reed instrument having a row of free reeds set back in air holes and played by blowing into the desired hole
What Scrabble words can I make with the letters in harp?
3 Letter Words
2 Letter Words