'coal-tar' originates from English, specifically the compound of 'coal' and 'tar', where 'coal' ultimately comes from Old English 'col' meaning 'coal' and 'tar' from Old Norse/Old English 'tārr'/'tǣr' meaning 'tar'.

'coal-tar' emerged as a compound term in the early 19th century to name the viscous residue produced by coal gasification and coke production; the separate words 'coal' and 'tar' are much older and were combined when industrial processes made coal tar a common substance.

Initially it meant 'the tar obtained from coal', and over time the term kept that core sense while also being used adjectivally (e.g., 'coal-tar soap', 'coal-tar pitch').