1550s, from Middle French cube (13c.) and directly from Latin cubus, from Greek kybos a cube, a six-sided die, vertebra, perhaps from PIE root *keu(b)- to bend, turn..
The triangle illustrates the three elements a fire needs to ignite: heat, fuel, and an oxidizing agent (usually oxygen). A fire naturally occurs when the elements are present and combined in the right mixture, meaning that fire is actually an event rather than a thing. A fire can be prevented or extinguished by removing any one of the elements in the fire triangle. For example, covering a fire with a fire blanket removes the oxygen part of the triangle and can extinguish a fire.
Fire is a very rapid chemical reaction between oxygen and a combustible material, which results in the release of heat, light, flames, and smoke. For fire to exist, the following four elements must be present at the same time: 1  Enough oxygen to sustain combustion. 2  Enough heat to raise the material to its ignition temperature. 3  Some sort of fuel or combustible material.  The chemical reaction that is fire.