Word of the Day – Deflagrate

Word of the Day : April 15, 2020


verb – DEF-luh-grayt


  • to burn rapidly with intense heat and sparks being given off
  • to cause (something) to burn in such a manner

Did You Know?

Deflagrate combines the Latin verb flagrare, meaning “to burn,” with the Latin prefix de-, meaning “down” or “away.” Flagrare is also an ancestor of such words as conflagration and flagrant and is distantly related to fulgent and flame. In the field of explosives, deflagrate is used to describe the burning of fuel accelerated by the expansion of gasses under the pressure of containment, which causes the containing vessel to break apart. In comparison, the term detonate (from the Latin tonare, meaning “to thunder”) refers to an instant, violent explosion that results when shock waves pass through molecules and displace them at supersonic speed. Deflagrate has been making sparks in English since about 1727, and detonate burst onto the scene at around the same time.


Certain materials, such as black powder, will deflagrate rather than cause a violent explosion when they are ignited.

“Classification of substances by their sensitivity to impact and friction is particularly important for the handling of explosives. Some explosives are known to detonate on impact, whereas others will only deflagrate.” — Jacqueline Akhavan, The Chemistry of Explosives, 2004.

Merriam-Webster Word of the Day