Translation guide
A flotation device worn to keep a person afloat in water. In Japanese, the most common term is 救命胴衣, but other terms exist depending on context.
The standard term for a life jacket, used in most everyday and official contexts.
The most common and general term for a life jacket. Used in safety instructions, on boats, and in aviation.
Please put on your life jacket.
Life jackets are provided on the boat.
Loanword from English, commonly used in casual contexts, outdoor sports, and leisure activities.
I wear a life jacket when canoeing.
Literally 'floating ring'. Refers to a ring-shaped flotation device, often used by children at the pool or beach. Not a full life jacket, but sometimes used loosely.
Not a proper life jacket; it's a swim ring. Do not use for safety equipment on boats.
The child is playing in the pool with a swim ring.
Specifically an inflatable type, often used in aviation or compact marine safety.
Technical term for an inflatable life jacket. Used in manuals and specifications.
This aircraft is equipped with inflatable life jackets.
救命胴衣 is the formal, official term used in safety regulations and announcements. ライフジャケット is a casual loanword common in sports and leisure. Both refer to the same object, but 救命胴衣 is preferred in written instructions and formal speech.