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Phrase(s): swan song
Fig. the last work or performance of a playwright, musician, actor, etc., before death or retirement. • His portrayal of Lear was the actor’s swan song. • We didn’t know that her performance last night was the singer’s swan song.
McGrawhill's American Idioms And Phrasal Verbs
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A final accomplishment or performance, one's last work. For example, I'm resigning tomorrow; this project was my swan song. This term alludes to the old belief that swans normally are mute but burst into beautiful song moments before they die. Although the idea is much older, the term was first recorded in English only in 1890.
American Heritage Idioms