Yes, gull is a Scrabble word!
...and is worth 5 points in Scrabble, and 9 points in Words with Friends
gull
Verb
1. Make a fool or dupe of
2. Fool or hoax
Noun
1. A person who is gullible and easy to take advantage of
2. Mostly white aquatic bird having long pointed wings and short legs
What Scrabble words can I make with the letters in gull?
3 Letter Words