Translation

The Japanese word for "Otter" is kawa-uso カワウソ.

Romaji ka wa u so
Hiraganaかわうそ
Katakanaカワウソ
Kanji 川 獺
Meaning River Otter
School Level 小1 ✕

Loan-word

The word "Otter" katakanized would be ottā オッター.
Romaji o ttaa
Katakanaオッター
Hiraganaおったー

Synonyms

Lutrinae.

Further Reading

Wikipedia: Otter (獺)