'single-lane' is a Modern English compound formed from the adjective 'single' and the noun 'lane'. 'single' originates from Old French 'sengle' (from Latin 'singulus'), where 'singul-' meant 'one, individual'; 'lane' originates from Old English 'lanu', meaning 'a narrow way or alley'.

'single' entered Middle English from Old French 'sengle' (derived from Latin 'singulus'), and 'lane' comes from Old English 'lanu'; the compound 'single-lane' developed in modern English by combining these words to describe a road with only one lane.

Initially, 'single' meant 'one' and 'lane' meant 'a narrow way'; when compounded, they described 'a way of one lane' and that basic meaning has been retained in modern usage as 'having only one lane'.