ETYM Old Eng. tinder, tunder, as. tynder, tyndre; akin to tendan to kindle, Dutch tonder tinder, German zunder, Old High Germ. zuntara, zuntra, Icel. tundr, Swed. tunder, Dan. tönder. Related to Tind.
Something very inflammable, used for kindling fire from a spark, as scorched linen.