Supine comes from Latin supinus ('lying on the back, face upward; also indolent'), related to sub ('under') and super ('above'), from Proto-Indo-European *upo ('under, up from under'). The historical chain includes Latin supinus and Proto-Indo-European *upo. The quoted older senses, "lying on the back, face upward; also indolent", "under", "above", and "under, up from under", supply the semantic anchors for supine. The formation is best read as borrowed: the word supine carries its older form-history into a compact English lexical shape. In present English it is used as a adj, "lying face upward; passively inactive". English derivatives include supinely, supineness, supinate, and supination; related English forms include supinate. The result is a adj and noun whose etymology preserves both the older form and the later English specialization.