IdiomDaily LifeFrench

Battre son plein

Meaning: To be in full swing.

Literally: To be at its full

Example: “À minuit, la fête battait son plein.” — At midnight, the party was in full swing.

English equivalent: In full swing

Equivalents in other languages

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Origin: Son here is the possessive, and plein is the full tide — the sea beating at its own high water. It is regularly misanalyzed as son meaning sound, which produces confident but wrong explanations.

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