aghast

Origin

From Middle English agast, agasted, past participle of agasten (“to terrify”), from Old English a- (compare with Gothic 𐌿𐍃- (us-), German er-, originally meaning "out") + gæstan (“to terrify, torment”): compare Gothic 𐌿𐍃𐌲𐌰𐌹𐍃𐌾𐌰𐌽 (usgaisjan, “to terrify”, literally “to fix, to root to the spot with terror”); akin to Latin haerere (“to stick fast, cling”). By surface analysis, a- + ghast/gast. See gaze.