Nautical. A pyrotechnic preparation which burns with a blue flame and is used to send signals, esp. at night-time. Now historical.

(a) an incendiary bomb; (b) (in the Caribbean) a conch or similar shell blown to raise the alarm in the event of a fire (rare).

= Bengal light n. at Bengal, n. compounds.

a kind of firework producing a steady and vivid blue-coloured light, used for signals; also figurative (see also quot. 1899).

a mixture of sulphur, realgar, and nitre, which burns with a brilliant white flame.

Nautical. A night-signal made by burning some highly inflammable material. Also flare-up light.

Nautical. (a) = flare-up, n. 3. Also in military, aeronautical, and general use; also attributive (see quots. 1918 1956 at sense 1b and flare path, n.…

Used attributively with reference to a coloured pyrotechnic flare projected from a special pistol for signalling or temporarily illuminating an…

= Very light at Very, n.2 Now rare.

a powerful lamp which can be turned rapidly on or off for signalling in Morse code.

An Aldis lamp.

= Bengal light n.

a buoyant pyrotechnic device used for illumination or as a signal, etc.