'nigh' originates from Old English, specifically the word 'nēah' (also written 'neah'), where the root meant 'near'.

'nēah' in Old English developed through Middle English forms such as 'nigh(e)', 'nyh' and eventually became the modern English 'nigh'. It is cognate with Old High German 'nāh' and German 'nah'.

Initially, it meant 'near' in a general spatial sense; over time it retained that core meaning but became more literary or archaic in usage and acquired senses like 'almost' or 'near in time'.