Any plant of the genus Nigella of about twelve species of annual flowering plants, the blooms of which are generally blue in colour but also found in shades of pink, white and pale purple.
A genus of ornamental plants of the polypetalous order <em>Ranunculaceæ</em>, the tribe <em>Helleboreæ</em>, and the subtribe <em>Isopyreæ</em>, known by the united carpels forming a compound ovary.