Rickets is a skeletal disorder caused by a vitamin D deficiency that results in a weakening of bones in children. The word, first used in a 1634 London mortality report, originated from a local dialect in southern England. Because of the provincial nature of the term, the etymology is uncertain, but there's been a lot of speculation on the topic. It could be from Old English wrickken, meaning "twist" (referring to how it can cause the spine to be abnormally curved), or from the Dorset word rucket, meaning "breathe with difficulty", or from Greek rakhis, "spine". The latter seems most likely; it comes from an earlier word meaning "ridge", which was most commonly used in reference to leaves and spines. Usage of the word peaked in 1939 and has been decreasing since.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.