Birthright rhymes with:
gathright, albright, allbright, argabright, arkwright, boatright, boatwright, cartwright, conkright, copyright, copywrite, courtright, courtwright, cronkright, curtright, cutright, displaywrite, downright, drumright, drumwright, femrite, fluorite, fulbright, fullbright, gathright, hambright, housewright, jinright, lambright, malrite, meteorite, playwright, plowright, rubright, seabright, seawright, shipwright, underwrite, wainright, wainwright, waybright, wegbreit, wheelwright, woolbright