The Collaborative International Dictionary
Onagraceous
Onagraceous \On`a*gra"ceous\ ([o^]n`[.a]*gr[=a]"sh[u^]s), Onagrarieous \On`a*gra*ri"e*ous\ (-gr[asl]*r[imac]"[-e]*[u^]s), a. [From NL. Onagra an old scientific name of the evening primrose ( [OE]nothera), fr. Gr. 'ona`gra 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).
Wiktionary
onagraceous
a. (context botany English) Of or relating to the family Onagraceae of flowering plants, including the fuchsia and the evening primrose.