mnl. delfijn, dolphijn, meerswijn
Dalfin is always used to designate the crown prince of France, never as a name for the animal. The other names are never used for the prince.
There is a problem with the meaning of delfijn/dolphijn and meerswijn. Sometimes the words mean the same, in other texts, however, the meerswijn is the porpoise/sea hog, and is distincted from the dolphin.