'shifty-eyed' originates from English, formed from the adjective 'shifty' + the adjectival/compound element 'eyed'; 'shifty' derives from 'shift' + suffix '-y' (where 'shift' meant 'move, change') and 'eyed' ultimately from Old English 'ēage' meaning 'eye'.

'shifty' developed in Middle English from a base related to 'shift' (Middle English 'shiften'/'shiften') with the adjectival suffix '-y', while 'eyed' comes from Old English 'ēage' plus a later adjectival use; the compound 'shifty-eyed' arose in modern English to describe someone with shifting or furtive eyes.

Initially it literally described someone 'having shifting eyes' (i.e., eyes that move around); over time it acquired the figurative sense of 'appearing untrustworthy or furtive'.