Unless guerrilla's comment was edited and you're referring to an older version, guerrilla's comment is completely correct. Aleph_1 doesn't refer to uncountable

Unless guerrilla's comment was edited and you're referring to an older version, guerrilla's comment is completely correct. Aleph_1 doesn't refer to uncountable cardinals in general, it's a specific uncountable cardinal. More specifically, it is, as guerrilla says, the number of countable ordinals.