General "up":
* en haut (pronounced "on oh") - This is the most common and general way to say "up".
* haut (pronounced "oh") - This can also be used as a standalone word, especially when describing location.
Other contexts:
* en l'air (pronounced "on lehr") - This means "in the air" and is used for things that are physically up.
* vers le haut (pronounced "vair le oh") - This means "towards the top" and is used for movement upwards.
* monter (pronounced "mon-tay") - This means "to go up" and is used for actions.
Examples:
* "The book is up on the shelf." - Le livre est en haut de l'étagère.
* "Look up at the sky." - Regarde en haut dans le ciel.
* "The airplane is flying up in the air." - L'avion vole en l'air.
* "Let's go up to the mountain." - Montons vers le haut de la montagne.
Note: The specific French word for "up" will vary depending on the specific situation and what you're trying to express.