How to say "dolphin" in Japanese

• いるかCommon
  nounThe common word for the marine mammal, covering dolphins and other small toothed whales such as porpoises and belugas. Choose this whenever 'dolphin' means the animal.
  イルカは哺乳類ほにゅうるいの一種いっしゅです。↗

  A dolphin is a kind of mammal.
• ドルフィン
  nounA loanword for the marine mammal dolphin. It is less common than いるか, so for the animal いるか is usually the word to reach for.
• しいら
  nounThe fish, not the mammal: this word means mahi-mahi (also called dorado or dolphinfish), which is one English sense of 'dolphin'. It is not the word for the marine mammal.
• マヒマヒ
  nounA loanword name for the same fish, the mahi-mahi that English sometimes calls 'dolphin'. Like しいら it has nothing to do with the marine mammal.

For the marine mammal, use 「いるか」, with the loanword 「ドルフィン」 as a less common alternative; for the fish that English can also call 'dolphin' (mahi-mahi), use 「しいら」 or 「マヒマヒ」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• いるかdolphin (or other small toothed whales, incl. porpoises, belugas, etc.)
• ドルフィンdolphin
• しいらmahi-mahi (Coryphaena hippurus)
• マヒマヒmahi-mahi (Coryphaena hippurus)