What's the adjective for denumerably? Here's the word you're looking for.
denumerable
(mathematics) Capable of being assigned numbers from the natural numbers. Especially applied to sets where finite sets and sets that have a one-to-onemapping to the natural numbers are called denumerable.
“The empty set is denumerable because it is finite; the rational numbers are, surprisingly, denumerable because every possible fraction can be assigned a number.”
“The non-denumerable infinity of real numbers is much larger than the merely denumerable infinity of integers.”
“The paper discusses denumerable sets, i.e. those which are in 1-1 correspondence with the natural numbers.”