thagomizer, n. The cluster of spikes at the end of a Stegosaurus’s tail.

Gary Larson, creator of The Far Side, crossed over into anatomical nomenclature with a 1982 comic in which a caveman teaches a class this faux-scientific word. (Larson later joked, “Father, I have sinned—I have drawn dinosaurs and hominids together in the same cartoon.”) But when fossil evidence suggested that the dinosaur used its stego-tail as a weapon, scientists co-opted the moniker. Ken Carpenter, a paleontologist at the Denver Museum of Nature and Science, was the first to use the term professionally, quipping, “And now, on to the thagomizer,” when describing a specimen with broken tail spikes at a 1993 meeting. These days, the word appears in reference books and museum exhibits. It’s no surprise that scientists adopted Larson’s terminology, says Carpenter. “He has a completely warped mind, which we absolutely love.”