cesspoolyoudaoicibaDictYouDict[cesspool 词源字典]
cesspool: [17] Cesspool has no direct etymological connection with pool. It comes from Old French suspirail ‘ventilator, breathing hole’, a derivative of souspirer ‘breathe’ (this goes back to Latin suspīrāre, source of the archaic English suspire ‘sigh’). This was borrowed into English in the early 15th century as suspiral ‘drainpipe’, which in the subsequent two hundred years appeared in a variety of spellings, including cesperalle.

By the early 16th century we find evidence of its being used not just for a pipe to drain matter away, but also for a well or tank to receive matter thus drained (originally any effluent, not just sewage). The way was thus open for a ‘reinterpretation’ of the word’s final element as pool (by the process known as folk etymology), and in the late 17th century the form cesspool emerged.

By analogy, as if there were really a word cess ‘sewage’, the term cesspit was coined in the mid-19th century.
=> suspire[cesspool etymology, cesspool origin, 英语词源]