The adjective profound means something that is felt or experienced very strongly or in an extreme way.

Synonyms are deep, thoughtful, serious, or subtle.

The word origins from Old French profund and Modern French (12th century) profond, from Latin profundus meaning “deep, bottomless, vast”, also “obscure, profound, immoderate”. It comes from pro meaning “forth” plus fundus meaning “bottom”.

His profound ideas amaze me.

She really admires his profound knowledge.

The novel was full of profound insights and information.