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Results found in several dictionaries: Collins, Collaborative Dictionary
vest pocket 
  n  (US) poche  f  de gilet

Collaborative Dictionary     English-French
vest pocket n. la poche de gilet Reverso General Dictionary 
! short jenny n. in off at billiards in middle pocket, jenny is pet for janet question;... 
authority vested in me n. une autorité qui m'a été confiée Reverso General Dictionary 
in pocket-size adj. en format de poche Reverso General Dictionary 
pocket format n. le format de poche Reverso General Dictionary 
in pocket format adj. en format de poche Reverso General Dictionary 
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'vest pocket' also found in translations in French-English dictionary
gilet pare-balles pref. bulletproof vest Reverso General Dictionary 
gilet pref. vest Reverso General Dictionary 
gilet de sécurité pref. safety vest Reverso General Dictionary 
calculette de poche nm. pocket calculator Reverso General Dictionary 
hélicoptère de poche pref. pocket helicopter Reverso General Dictionary 
mouchoir de poche pref. pocket handkerchief Reverso General Dictionary 
grand comme un mouchoir de poche exp. the size of a pocket handkerchief Reverso General Dictionary 
grande comme un mouchoir de poche exp. the size of a pocket handkerchief Reverso General Dictionary 

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