One of the mysteries of the English language finally explained.
1Military slang (now historical). Originally: a soldier belonging to the Royal Madras Fusiliers; (later) a soldier belonging to the Royal Dublin Fusiliers.
2Chiefly English regional. The cornflower, Centaurea cyanus. Now rare.
3A bluish layer in a flame; specifically (Mining) a circle of bluish flame appearing above and around the wick of a safety lamp, indicating the presence of explosive gases. Compare "cap". Now rare.
Late 16th century (in an earlier sense). From blue + cap.
blue cap/ˌbluː ˈkap/
In this article we explore how to impress employers with a spot-on CV.