thunderhead (n.)youdaoicibaDictYouDict[thunderhead 词源字典]
"high-piled cumulus cloud," one likely to develop into a thunderstorm, 1861, from thunder (n.) + head (n.).[thunderhead etymology, thunderhead origin, 英语词源]
rupiayoudaoicibaDictYouDict
"A skin disease in which there is an eruption of vesicles or pustules which develop into ulcerated sores covered by thick, dark scabs or crusts; especially a form of secondary syphilis characterized by such lesions", Early 19th cent.; earliest use found in Thomas Bateman (1778–1821), physician and dermatologist. From scientific Latin rupia from ancient Greek ῥύπος dirt, filth + classical Latin -ia.
ulcerateyoudaoicibaDictYouDict
"Develop into or become affected by an ulcer", Late Middle English: from Latin ulcerat- 'made ulcerous', from the verb ulcerare.