Translation

The Japanese word for "Weasel" is itachi イタチ.

Romaji i ta chi
Hiragana
Katakana
Kanji
Meaning Weasel
School Level

Loan-word

The word "Weasel" katakanized would be wīzeru ウィーゼル.
Romaji wii ze ru
Katakanaウィ
Hiraganaうぃ

Further Reading

Wikipedia: Weasel ()