noun: Visible light towards the blue end of the spectrum generated from the screen of an electronic device.
noun: (historical, uncountable) A mixture of chemicals (including nitre, sulfur and antimony) used in eighteenth and nineteenth centuries for pyrotechnics, night-time signaling and general illumination.
noun: (historical, figuratively) Someone or something that physically resembles the illuminating bright glow and/or displays a zeal figuratively reminiscent of the ardent burning intensity of the pyrotechnic light signal used in the eighteenth and nineteenth centuries.
noun: (countable) A flashing light, usually fitted to an emergency vehicle.
noun: Used other than figuratively or idiomatically: see blue, light.
verb: To travel quickly in a police or ambulance vehicle with the lightbar (and possibly the siren) activated.