This is the 3215th most frequent French word.
reçues
"Reçues" means "received."
Here, "reçues" (received) serves as a past participle in the feminine plural form, agreeing with the plural feminine noun "lettres."
Les lettres reçues hier étaient pleines de bonnes nouvelles.
The letters received yesterday were full of good news.
In this sentence, "reçues" (preconceived or literally received) is used as an adjective, modifying the noun "idées," which is feminine plural.
Elle a lu toutes les idées reçues sur ce sujet pour se préparer.
She read all the preconceived ideas on this subject to prepare herself.
Here, "reçues" is the past participle of the verb "recevoir," agreeing with the feminine plural noun "justifications."