(Anglo-Saxon, el-boga, el = an ell, boga = a
A knight of the elbow.
A gambler. At one's elbow. Close at hand. To elbow one's
way in. To push one's way through a crowd; to get a place by hook
or crook. To elbow out, to be elbowed out. To supersede; to be
ousted by a rival.
Up to one's elbow
[in work]. Very busy, or full of work. Work piled up to one's
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894