Onagraceous \On`a*gra"ceous\, Onagrarieous \On`a*gra*ri"e*ous\, a. [From NL. Onagra an old scientific name of the evening primrose (Enothera), fr. Gr. ? a kind of plant; of uncertain origin.]

(Bot.) Pertaining to, or resembling, a natural order of plants (Onagrace[ae] or Onagrarie[ae]), which includes the fuchsia, the willow-herb (Epilobium), and the evening primrose ([OE]nothera).

Source: Webster's Revised Unabridged Dictionary (1913)