Masterwort \Mas"ter*wort`\, n. (Bot.)
   (a) A tall and coarse European umbelliferous plant (Peucedanum Ostruthium, formerly Imperatoria).
   (b) The Astrantia major, a European umbelliferous plant with a showy colored involucre.
   (c) Improperly, the cow parsnip (Heracleum lanatum).

Source: Webster's Revised Unabridged Dictionary (1913)