The Collaborative International Dictionary of English v.0.48:
Onagra \O*nag"ra\, prop. n. (Bot.) Same as Oenothera, a genus of plants consisting of the evening primrose. [PJC]The Collaborative International Dictionary of English v.0.48:
onagra \on"a*gra\, n. The female of the onager. [PJC] Onagraceous