fossil

noun6

1. •
   The mineralized remains of an animal or plant.

   • With the permission of the Keeper of the fossil collection, therefore, the specimen was subjected to a further careful removal of the matrix in the requisite directions. — 1870
2. •
   Any preserved evidence of ancient life, including shells, imprints, burrows, coprolites, and organically-produced chemicals.

   • He draws eclectically on studies of baboons, descriptive anthropological accounts of hunter-gatherer societies and, in a few cases, the fossil record. — 2012
3. •
   (figurative) Anything extremely old, extinct, or outdated.
4. •
   (disapproving, figurative) An extremely old or outdated person.

   • All at once there was a tapping at the window pane. Atherton was staring at us from without. He shouted through the glass, ‘Come out of that, you fossils! — I’ve news for you!’ — 1897
5. •
   A fossil word.
6. •
   (Internet, informal) A piece of content, which, despite its age, is being repromoted to a large volume of users by the algorithm.