1. Inflammation of a vein; when accompanied by thrombus formation it is called thrombophlebitis.
2. Inflammation of a vein which is marked by infiltration of the coats of the vein and the formation of a thrombus (vascular obstruction).

There is pain and tenderness along the course of the vein, discoloration of the skin, inflammatory swelling and acute edema (excessive amount of tissue fluid) below the obstruction, rapid pulse, mild elevation of temperature, and pain in the joints.