late 13c., from Old French hostage "person given as security or hostage" (12c., Modern French ôtage), either from hoste "guest" (see host, n.1) via notion of "a lodger held by a landlord as security," or from Late Latin obsidanus "condition of being held as security," from obses "hostage," from ob- "before" + base of sedere "to sit" [OED]. Modern political/terrorism sense is from 1970.