'cornerways' originates from English, specifically formed from 'corner' + 'ways', where 'corner' ultimately comes from Old French (from Latin 'cornu') meaning 'horn' (used of projecting angles) and 'way' comes from Old English 'weg' meaning 'path' or 'manner'.

'corner' developed in Middle English from Old North French and Late Latin influences to denote an angular projection; combined with Middle English 'way(s)' (from Old English 'weg') it produced compounds like 'cornerwise' and 'cornerways' used to indicate direction or manner associated with a corner.

Initially the elements referred to a 'horn/angle' (corner) and a 'way' (path or manner); over time the compound came to mean 'in the manner of a corner'—i.e., 'diagonally' or 'toward a corner'—a usage that has become somewhat archaic or dialectal.