There are several synonyms for the phrase "bend elbow". The most common synonym is "flex arm", which refers to the action of flexing or bending the arm at the elbow joint. Another synonym for "bend elbow" is "crook arm", which describes the position of the elbow joint when it is bent or flexed. Additionally, "bend forearm" is another synonym some people might use to describe the motion of bending the elbow. Whatever phrase one uses, the action of bending the elbow is a common movement in our daily lives, whether it's reaching for something or making a gesture.