Definition
"Denumerable" describes a set that can be put into a one-to-one correspondence with the natural numbers (1, 2, 3...). It implies items which can be listed, even if the list is infinitely long. Think of it as potentially "countable" but possibly infinite. A "denumerable" set can be counted, one by one, even if you never reach the end. Unlike an 'uncountable' set, you can conceptually create a list.