1a. In a somersault; upside down; head first. It was so dark Bob fell head over heels into a big hole in the ground.
Compare: UPSIDE DOWN. 1b. In great confusion or disorder; hastily. The children all tried to come in the door at once, head over heels.
Compare: TOPSY-TURVY. 2. informal Completely; deeply. He was head over heels in debt. She was head over heels in love.