porpoiseyoudaoicibaDictYouDict[porpoise 词源字典]
porpoise: [14] The porpoise is etymologically the ‘pig-fish’. The word comes via Old French porpois from Vulgar Latin *porcopiscis, a compound formed from porcus ‘pig’ (source of English pork) and piscis ‘fish’ (a relative of English fish) and based on the model of Latin porcus marīnus ‘sea-pig’. The name may have been suggested by the porpoise’s snout.
=> fish, pork[porpoise etymology, porpoise origin, 英语词源]
porpoise (n.)youdaoicibaDictYouDict
early 14c., porpas, from Old French porpais (12c.) "porpoise," literally "pork fish," from porc "pork" (see pork (n.)) + peis "fish," from Latin piscis "fish" (see fish (n.)).

The Old French word probably is a loan-translation of a Germanic word meaning literally "sea-hog, mere-swine," such as Old Norse mar-svin, Old High German meri-swin, Middle Dutch mereswijn "porpoise" (the last of which also was borrowed directly into French and became Modern French marsouin).

Classical Latin had a similar name, porculus marinus (in Pliny), and the notion behind the name likely is a fancied resemblance of the snout to that of a pig.