1
general::
1. To a position higher than another's, as in She was furious when her assistant was promoted over her head. Similarly, go over someone's head means "appeal to a higher authority," as in Since she couldn't help me, I decided to go over her head and talk to her supervisor. [Mid-1500s] 2. Beyond one's understanding or competence, as in The math required to complete these figures is way over my head. [Early 1600s] For a synonym, see OUT OF ONE'S DEPTH. Also see IN DEEP (OVER ONE'S HEAD).
American Heritage Idioms