The Collaborative International Dictionary
Over-arm \O"ver-arm`\, a. (Cricket, etc.)
Done (as bowling or pitching) with the arm raised above the
shoulder. See Overhard. ``An over-arm with a round-arm
bowler.''
--R. A. Proctor.
Wikipedia
An over-arm position is a posture in which a person's arms are extended over their shoulders or behind their head. This may take place, for example, during work or a sporting activity, and is used in stretching exercises or during meditation besides other activities. In wrestling, for example, nelson holds are over-arm holds, in a contest for physical dominance. In cricket, over-arm bowling is the norm. Also, in law enforcement the raising of the arms above or behind the head is a gesture of surrender or submission, as it is in a military situation.
Usage examples of "over-arm".
With only two Galaxy class and two destroyers, one of them minus significant numbers of its ordinary complement, she is not really equipped to tackle two or more Hivers and their complement of over-armed scouts.
Daniel shoved it away like a shot put instead of using an over-arm motion the way he'd started to.