1580s, from Dutch or Low German belegeren "to besiege," from be- "around" (see be-) + legeren "to camp," from leger "bed, camp, army, lair," from Proto-Germanic *leg-raz-, from PIE *legh-to- "lie" (see lie, v.2). A word from the Flemish Wars (cognates: Swedish belägra, Dutch belegeren "besiege," German Belagerung "siege"). Spelling influenced by league. Related: Beleaguered; beleaguering.