Yes, fins is a Scrabble word!
...and is worth 7 points in Scrabble, and 8 points in Words with Friends
fins
Verb
1. Equip (a car) with fins
2. Propel oneself through the water in a finning motion
3. Show the fins above the water while swimming
Noun
1. The cardinal number that is the sum of four and one
2. One of a pair of decorations projecting above the rear fenders of an automobile
3. One of a set of parallel slats in a door or window to admit air and reject rain
4. A shoe for swimming; the paddle-like front is an aid in swimming (especially underwater)
5. A stabilizer on a ship that resembles the fin of a fish
6. Organ of locomotion and balance in fishes and some other aquatic animals
What Scrabble words can I make with the letters in fins?
3 Letter Words
2 Letter Words