Translation

wīzeru means "Weasel" in English.
It's a katakanization, a loan-word.

wīzeru is normally written with katakana, as ウィーゼル.
wīzeru written with hiragana is うぃーぜる.
wīzeru does not have kanji.
Romaji wii ze ru
Katakanaウィ
Hiraganaうぃ

Orthography Notes

Synonyms

Further Reading

Wikipedia: (Weasel)
nihon-itachi 日本鼬.