1. noun The act of touching the knuckle side of one's clenched fist with someone else's, either as a greeting or in a cheerful or celebratory manner. Also known as a "pound." He was so excited by the team's overtime win that he gave everyone fist bumps as we left the stadium.

2. verb To touch one's clenched fist with someone else's in such a manner. He was so excited by the team's overtime win that he was fist bumping everyone as we left the stadium.