Meaning

noun childhood disease caused by deficiency of vitamin D and sunlight associated with impaired metabolism of calcium and phosphorus

originUnknown. Originally a local name for the disease in Dorset and Somerset, England. Occasionally postulated to be derived from a Dorsetian dialectal term *rucket (“to breathe with difficulty, wheeze”), but the semantic connection is tenuous. See rachitis, but the medical name was chosen purposefully by English physician Daniel Whistler from phonetic similarity to rickets.

Etymology from Wiktionary, CC BY-SA 3.0