Sovereign  —n. 1 supreme ruler, esp. A monarch. 2 hist. British gold coin nominally worth £1. —adj. 1 supreme (sovereign power). 2 self-governing (sovereign state). 3 royal (our sovereign lord). 4 excellent; effective (sovereign remedy). 5 unmitigated (sovereign contempt). [french so(u)verain: -g- by association with reign]