Yes, barb is a Scrabble word!
...and is worth 8 points in Scrabble, and 10 points in Words with Friends
barb
Verb
1. Provide with barbs
Noun
1. An aggressive remark directed at a person like a missile and intended to have a telling effect
2. The pointed part of barbed wire
3. A subsidiary point facing opposite from the main point that makes an arrowhead or spear hard to remove
4. One of the parallel filaments projecting from the main shaft of a feather
What Scrabble words can I make with the letters in barb?
3 Letter Words
2 Letter Words