Definition of flexion
1
: the act of flexing or bending
2
: a part bent : bend
3
: inflection 3
4 a
: a bending movement around a joint in a limb (such as the knee or elbow) that decreases the angle between the bones of the limb at the joint — compare extension 3b
b
: a forward raising of the arm or leg by a movement at the shoulder or hip joint
