Otter
Old English otr, ot(t)or, of Germanic origin; related to Greek hudros ‘water snake’.
wiktionary
From Middle English oter, otir, otur, otyre, from Old English otor, from Proto-West Germanic *ot(t)r, from Proto-Germanic *utraz, from Proto-Indo-European *udrós(“aquatic, water-animal”), from Proto-Indo-European *wed-(“water”).
Cognate with Saterland Frisian Otter, Dutch otter, German Otter, Swedish utter, Norwegian oter, Icelandic otur, Sanskrit उद्र(udrá), Russian вы́дра(výdra), and Ancient Greek ὕδρα(húdra, “water snake”). More etymology under English water.
Corruption of annotto.
etymonline
otter (n.)
aquatic digitigrade carnivorous mammal, hunted for its fur, Middle English oter, from Old English otr, otor "otter," from Proto-Germanic *otraz "otter" (source also of Old Norse otr, Swedish utter, Danish odder, Dutch otter, Old High German ottar, German Otter), from PIE *udros, literally "water-creature" (source also of Sanskrit udrah, Avestan udra "otter;" Greek hydra "water-serpent," enydris "otter;" Latin lutra, Old Church Slavonic vydra, Lithuanian ūdra, Old Irish odoirne "otter"), from root *wed- (1) "water; wet." The sea otter of the U.S. Pacific Northwest is attested from 1660s, also known as sea-ape.
