“Piquant” comes from the French, translating directly as “stinging, pricking,” but there’s a much more enjoyable connotation in English. The adjective is most commonly applied to food, where “piquant” means “something pleasantly sharp and appetizing.” It’s flavorful and robust, but not too spicy or jarring. “Piquant” can also be used in an intellectually stimulating sense — it excites the mind, but again, in a pleasant manner.