gristle

Etymology

From Middle English gristel, grystyl, from Old English gristel (“gristle, cartilage”), formed from a diminutive of Old English grist (“a grinding”), from Proto-Germanic *gredaną (“to crunch”), equivalent to grist + -le. Cognate with Old Frisian gristel, gerstel (“gristle, cartilage”), Middle Low German gristel (“gristle”).

noun

1. Cartilage; now especially: cartilage present, as a tough substance, in meat.
   When you're chewing on life's gristle Don't grumble, give a whistle And this'll help things turn out for the best[…] 1979, Monty Python (lyrics and music), “Always Look on the Bright Side of Life”
   But she was tired of cell culture, tired of meticulously cutting away dead tissue like gristle from a steak […] 2011, Rebecca Skloot, The Immortal Life of Henrietta Lacks, New York: Broadway Books, page 35
2. (figurative, from obsolete scientific theory) Bone not yet hardened by age and hard work.
   1885, Ada Sarah Ballin, The Science of Dress in Theory and Practice, It. must be borne in mind that the bones of a young infant are little more than gristle, and are liable to bend, and so become deformed.
   "The young 'un will make his way," said Belcher, who had come across to us. "He's more a sparrer than a fighter just at present, but when his gristle sets he'll take on anything on the list. 1896, Arthur Conan Doyle, Rodney Stone, (Please provide the book title or journal name)