Rugged comes from Middle English rugged ('rough, shaggy'), probably of Scandinavian origin, akin to Old Norse rögg ('tuft, shagginess'), the source also of 'rug'. The historical chain includes Old Norse rögg. The quoted older senses, "rough, shaggy", "tuft, shagginess", and "rug", supply the semantic anchors for rugged. The formation is best read as borrowed: the word rugged carries its older form-history into a compact English lexical shape. In present English it is used as a adj, "having a rough, uneven surface or a tough, sturdy character". English derivatives include ruggedly and ruggedness; related English forms include rug. The result is a adj whose etymology preserves both the older form and the later English specialization.