Unclean comes from Old English unclæne ('unclean, impure'), from un- ('not') + clæne ('clean, pure'), from Proto-West-Germanic *klaini ('clear, pure, fine'), of uncertain further origin. The historical chain includes Old English unclæne and Old English clæne. The quoted older senses, "unclean, impure", "not", "clean, pure", and "clear, pure, fine", supply the semantic anchors for unclean. The formation is best read as compound and borrowed: the word unclean carries its older form-history into a compact English lexical shape. In present English it is used as a adj, "dirty; morally or ritually impure". English derivatives include uncleanness, uncleanly, and uncleanliness; related English forms include clean, cleanly, and cleanliness. The result is a adj whose etymology preserves both the older form and the later English specialization.