Bluecap

noun

1. A fish said to be of the salmon kind, with blue spots on its head.
2. Same as bluebonnet
3. In botany: Some blue-flowered species of Scabiosa, as S. succisa and S. arvensis. The bluebottle, Centaurea Cyanus.
4. Same as bluebonnet, 3.
5. In coal-mining, a blue or brownish halo around the flame of the safety-lamp, indicating the presence of a dangerous quantity of fire-damp.