tinderbox

• tinder-box, tinder box

tinder +‎ box, first use appears c. 1530, in the writings of John Palsgrave.

tinderbox (plural tinderboxes)

1. (historical) A small container containing flint, steel, and tinder (dry, finely-divided fibrous matter), once used to help kindle a fire.
   • 1922 February, James Joyce, “[Episode 1: Telemachus]”, in Ulysses, Paris: Shakespeare and Company, […], →OCLC, part I [Telemachia], pages 19–20:

     Haines helped himself and snapped the case to. He put it back in his sidepocket and took from his waistcoatpocket a nickel tinderbox, sprang it open too, and, having lit his cigarette, held the flaming spunk towards Stephen in the shell of his hands.

   • 2007, Stephen Mitchell, The Tinderbox, page 5:

     Just bring me the old tinderbox that my grandmother forgot the last time she went down there.

2. (by extension) A place that is so dry and hot that there is danger of fire.
   • 1974, Harry Chapin (lyrics and music), “What Made America Famous”, in Verities & Balderdash:

     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

   • 2010, L. K. Ludwig, Creative Wildfire: An Introduction to Art Journaling, page 30:

     Think of your blank journal as a tinderbox, a box for holding combustible materials, ready to catch fire when you sit down to work.

3. (figurative) A potentially dangerous situation.
   • 2010, H. S. Haskell, Sagebrush Or Gold Dust, page 291:

     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.

(potentially dangerous situation):

• powder keg, powderkeg, powder magazine

• box

• tinderbox on Wikipedia.Wikipedia
• “tinderbox”, in OneLook Dictionary Search.
• tinderbox, tinder-box at Google Ngram Viewer