This is the 2071st most frequent French word.
seuls
"Seuls" means "alone" or "only" (plural).
The word 'seuls' is used as an adjective meaning 'alone', agreeing in number (plural) and gender (masculine) with 'les enfants'.
Les enfants étaient seuls dans la maison.
The children were alone in the house.
Here, 'seuls' functions as an adjective meaning 'only' and agrees in number (plural) and gender (masculine) with 'les livres'.
Ce sont les seuls livres qu'il a conservés.
These are the only books he kept.
In this sentence, 'seuls' emphasizes exclusivity, used as an adjective agreeing in number (plural) and gender (masculine) with 'experts'.