This is the 8627th most frequent Japanese word.
救命胴衣
Life jacket.
The word '救命胴衣' here is used as the object (a life jacket) of the action of putting on and wearing.
救命胴衣を着てボートに乗り込みました。
I put on a life jacket and boarded the boat.
The word '救命胴衣' is described as an item to be remembered and brought.
救命胴衣を忘れないで持ってきてくださいね。
Don't forget to bring your life jacket.
The term '救命胴衣' is mentioned in the context of discussing its significance and role.