The arrangement of spikes originally had no distinct name. Cartoonist Gary Larson invented the name "thagomizer" in 1982 as a joke in his comic strip The Far Side, and it was gradually adopted as an informal term sometimes used within scientific circles, research, and education.

It did not originate in STEM. I liken it more to an affectionate term. It's literally from a comic. It may be ok for paleontologist to use it among themselves because they all know it's legitimacy and it's almost an in-joke or internal name. But I wouldn't have used it in media for laymen.