ab·sin·thi·um \abˈsin(t)thēəm\noun (pluralabsinthium) Etymology: Middle English, from Latin, from Greek apsinthion 1.: wormwood 2. a.: the dried leaves and flowering tops of a common wormwood (Artemisia absinthium) once used as a bitter tonic and stomachic b.: oil of wormwood used as an ingredient of absinthe