au-dedans

Unlike English, French uses 'au-dedans' as an adverb or a noun, not typically as a preposition directly before a noun. You'd usually use 'dans' or 'à l'intérieur de' for 'inside of' something.

Il est au-dedans. (He is inside.) vs. Il est dans la maison. (He is in the house.)

When 'au-dedans' refers to the interior of something abstract or metaphorical, it maintains its 'inside/within' meaning.

Il y a une tempête au-dedans de moi. (There is a storm within me.)

It can be used with 'de' to specify 'inside of' something, but this construction is more common with abstract concepts or when emphasizing the internal aspect.

La beauté est au-dedans de nous. (Beauty is within us.)

When used as a noun, 'l'au-dedans' refers to the interior or the inside, often in a more philosophical or abstract sense.

Il faut explorer l'au-dedans. (One must explore the interior/what's within.)

Pay attention to the nuance. 'Au-dedans' often implies a deeper or more internal 'inside' compared to 'dedans' which is a more general 'inside' or 'in'.

Il a cherché au-dedans de lui-même. (He searched deep within himself.) vs. Le livre est dedans. (The book is inside [e.g., in the bag]).