Translation

The Japanese word for "Caribou" is tonakai トナカイ.

Romaji to na ka i
Hiraganaとなかい
Katakanaトナカイ
Kanji 馴鹿
Meaning Tamed Deer
School Level ✕, 中

Loan-word

The word "Caribou" katakanized would be karibū カリブー.
Romaji ka ri buu
Katakanaカリブー
Hiraganaかりぶー

Trivia

Synonyms

Scientific name: Rangifer tarandus.

Further Reading

Wikipedia: Reindeer (トナカイ)