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A concern or worry that occupies someone's mind.
Elle a exprimé ses préoccupations concernant l'environnement.
She expressed her concerns about the environment.
Often used in the plural to indicate multiple worries.
While 'préoccupation' can be used in both singular and plural forms, the plural is more common when referring to multiple concerns.
From Old French 'preocupacion', from Latin 'praeoccupatio' (preoccupation), from 'praeoccupare' (to occupy beforehand).
Can be used in both formal and informal contexts, but often carries a slightly more formal tone than 'souci'.