'clean-looking' originates from Modern English, specifically the words 'clean' (Old English 'clǣne') and 'look' (Old English 'lōcian'), where 'clean' meant 'free from dirt, pure' and 'look' meant 'to see or to appear.'

'clean' developed from Old English 'clǣne' through Middle English 'clene' into modern English 'clean'; 'look' developed from Old English 'lōcian' to Middle English 'loken/looken' and modern English 'look', with the present participle forming 'looking'. The compound adjective 'clean-looking' arose in Modern English by combining these elements to describe appearance.

Initially, 'clean' emphasized purity or absence of dirt and 'look' meant 'to seem or appear'; over time the compound came to mean 'appearing neat or free of clutter' (i.e., 'seeming clean').