Translation

shāku means "Shark" in English.
It's a katakanization, a loan-word.

shāku is normally written with katakana, as シャーク.
shāku written with hiragana is しゃーく.
shāku does not have kanji.
Romaji shaa ku
Katakanaシャ
Hiraganaしゃ

Orthography Notes

Synonyms

Further Reading

Wikipedia: サメ (Shark)