secret of Polichinelle

Etymology
From, from a play by.

Noun

 * 1) A supposed secret known to everyone.

Translations

 * Finnish: julkinen salaisuus
 * French:
 * Hebrew: סוד גלוי
 * Italian: segreto di Pulcinella
 * Polish:
 * Russian:, секре́т — на весь све́т