Source : Webster's Revised Unabridged Dictionary (1913)

Sundrops \Sun"drops`\, n. [Sun + drop.] (Bot.)
   Any one of the several species of {Kneiffia}, esp. {K.
   fruticosa} (syn. {[OE]nothera fruticosa}), of the
   Evening-primrose family, having flowers that open by
   daylight.

Source : WordNet®

sundrops
     n : a day-flowering biennial or perennial of the genus Oenothera
         [syn: {Oenothera fruticosa}]