Yes, barb is a Scrabble word!

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