elbow bump

Short definition from Wiktionary

Noun

1. 1
   A hit to the elbow; also, an injury to the elbow caused by such a hit.
2. 2
   A hit or jab made with the elbow.
3. 3
   The touching of elbows between two people, sometimes as an alternative to a handshake, fist bump, or other form of contact when attempting to avoid the spread of germs.