blue light

blue light (countable and uncountable, plural blue lights)

1. (historical, chiefly nautical) A mixture of chemicals (including nitre, sulfur and antimony) used in the eighteenth and nineteenth centuries for night-time signaling and general illumination.
   • 1828, Samuel Frederick Gray, The Operative Chemist, page 499:

     Blue lights, or blue fire, is a preparation in which zinc and sulphur, or sulphur alone, are used. The particular colour is communicated by the zinc and sulphur.

   • 1874, Marcus Clarke, For the Term of his Natural Life, Penguin, published 2009, page 57:

     The blue-light, which, at its first flashing over the ocean, had made the very stars pale their lustre, and lighted up with ghastly radiance the enormous vault of heaven, was now only a point […] .

   • 2015, Mark K. Ragan, quoting Robert Fleming, Proceedings of a Naval Court of Inquiry into the Sinking of the Housatonic, 1864, quoted in Confederate Saboteurs, Texas A&M University Press, →ISBN, page 98:

     When the 'Canandaigua' got astern, and was lying athwart, of the 'Housatonic,' about four ship lengths off, while I was in the fore rigging, I saw a blue light on the water just ahead of the 'Canandaigua,' and on the starboard quarter of the 'Housatonic.'

2. (US, colloquial, now historical) A New England federalist, who opposed the Anglo-American War of 1812; (loosely), a federalist.
   • 1862, John Williamson Palmer, Stonewall Jackson's Way :

     The “Blue-Light Elder” knows ’em well; / Says he, “That’s Banks — he’s fond of shell; / Lord save his soul! We’ll give him” — well, / that’s “Stonewall Jackson’s Way.”

3. (countable) A flashing light, usually fitted to an emergency vehicle.
   • 2019 October, Roger Ford, “Power failure highlights specification confusion”, in Modern Railways, page 26:

     Blue-light escorts were provided where possible to get engineers to the stranded GTR trains to reset the software.

4. (Should we delete⁽⁺⁾ this sense?) Visible light towards the blue end of the spectrum generated from the screen of an electronic device.
5. Used other than figuratively or idiomatically: see blue,‎ light.

The original chemical mixtures burned with a blue flame. Later versions omitted any colouring agents, producing a bright white light, but retained the name by convention.

• (chemicals): Bengal fire, Bengal light
• (flashing lights): cherry light, lightbar

• light

• blue light bandit

• Blue light (pyrotechnic signal) on Wikipedia.Wikipedia
• Emergency vehicle lighting on Wikipedia.Wikipedia

blue light (third-person singular simple present blue lights, present participle blue lighting, simple past and past participle blue lighted)

1. To travel quickly in a police or ambulance vehicle with the lightbar (and possibly the siren) activated.
   • 2011, John Donoghue, Police, Crime & 999, Troubador Publishing, →ISBN:

     When we weren't blue lighting, we had to obey the 30 mph limit, but out of town we had a training exemption from any speed regulations and were encouraged to push the car to its limits... and we did.

   • 2012, Jon Mukand, The Man with the Bionic Brain, Chicago Review Press, →ISBN:

     They jumped into his cruiser and blue-lighted it to Boston Medical Center at eighty miles per hour.

   • 2014, James Rennie, The Operators, Pen and Sword, →ISBN:

     Roger that. Feds and green army are blue lighting to you.

• See Thesaurus:move quickly

• “blue light”, in Lexico, Dictionary.com; Oxford University Press, 2019–2022.

• light blue