The infant will probably get a contact high, but Marijuana is not physically addictive, so the child, or anyone for that matter, becoming addicted is impossible. Regardless, it's not a good idea, and highly morally questionable.
Quite literally the same thing: a pot. This does not refer however to the English slang word for "Marijuana" informally known as "pot". "Un pot" in french refers to a flower pot for example or a clay pot.