This is the 1116th most frequent French word.
cinquantaine
A group of about fifty or the age of fifty.
Cinquantaine is used here to approximate a quantity around fifty.
Il y avait une cinquantaine de personnes à la fête.
There were about fifty people at the party.
Cinquantaine refers to an approximate age range, typically denoting the fifties.
Il a une cinquantaine d'années, mais il semble plus jeune.
He is in his fifties, but he looks younger.
Cinquantaine stands for a decade of life, specifically from fifty to sixty.