Unalike comes from un- ('not') + alike, the latter from Old English gelic ('similar'), from Proto-Germanic *galika- ('having the same form'), from *ga- (collective prefix) + *likan ('body, form'). The historical chain includes Old English un-, Old English gelic, and Proto-Germanic *galika-. The quoted older senses, "not", "similar", "having the same form", and "body, form", supply the semantic anchors for unalike. The formation is best read as prefixal, compound, and borrowed: the word unalike carries its older form-history into a compact English lexical shape. In present English it is used as a adj, "not similar; different". Related English forms include alike, like, and likeness. The result is a adj whose etymology preserves both the older form and the later English specialization.