The Collaborative International Dictionary of English v.0.48:

Tinder \Tin"der\, n. [OE. tinder, tunder, AS. tynder, tyndre;
   akin to tendan to kindle, D. tonder tinder, G. zunder, OHG.
   zuntara, zuntra, Icel. tundr, Sw. tunder, Dan. t["o]nder. See
   Tind.]
   Something very inflammable, used for kindling fire from a
   spark, as scorched linen.
   [1913 Webster]

   German tinder. Same as Amadou.

   Tinder box, a box in which tinder is kept.
      [1913 Webster]
      [1913 Webster]

WordNet (r) 3.0 (2006):

tinder
    n 1: material for starting a fire [syn: kindling, tinder,
         touchwood, spunk, punk]