Title: Theory / Unimportant / Math / Logic / Set Theory / wp;

Page: https://en.wikipedia.org/wiki/First_uncountable_ordinal,
Notation: \(\omega_1\)
Definition: The supremum (least upper bound) of all countable ordinals
Context: Ordinal
Intuition: Smallest ordinal number that, considered as a set, is uncountable
Name: First uncountable ordinal
Notation2: \(\Omega\)
Limit/successor: limit
Axiom: without AC