the.com/scuba

means A type of diving gear with a tank of compressed air that lets you breathe underwater without a surface line.

from Born as military jargon: SCUBA started life capitalized, standing for 'Self-Contained Underwater Breathing Apparatus,' coined in the 1950s to describe gear that freed divers from the heavy helmets and surface air-hoses of older diving suits. Like radar and laser, it was an acronym so useful it eventually lowercased itself into an ordinary noun — and then, inevitably, a verb.