tinderbox

Etymology

tinder + box

noun

1. (historical) A small container containing flint, steel, and tinder (dry, finely-divided fibrous matter), once used to help kindle a fire.
   Just bring me the old tinderbox that my grandmother forgot the last time she went down there. 2007, Stephen Mitchell, The Tinderbox, page 5
2. (by extension) A place that is so dry and hot that there is danger of fire.
   And then came the night that made America famous / Was it carelessness or someone's sick idea of a joke? / In the tinderbox trap that we hippies lived in, someone struck a spark 1974, Harry Chapin (lyrics and music), “What Made America Famous”, in Verities & Balderdash
   Think of your blank journal as a tinderbox, a box for holding combustible materials, ready to catch fire when you sit down to work. 2010, L. K. Ludwig, Creative Wildfire: An Introduction to Art Journaling, page 30
3. (figurative) A potentially dangerous situation.
   This act was the "match that ignited the great tinderbox of fuel" that had been building for years between many of the countries in Europe. 2010, H. S. Haskell, Sagebrush Or Gold Dust, page 291