Are cardinal numbers well defined? Or could we have something like $\aleph_{1/2}$?
30519
"Real" cardinality, say, $\aleph_\pi$?
63489
The class of cardinal numbers is well ordered
32081
The dual version of trichotomy of cardinality without AC
86914
Cardinality of the set of hyperreal numbers
105594
Fixed point, union of $\aleph_0, \aleph_{\aleph_0},\aleph_{\aleph_{\aleph_0}}\dots$ [see Noah's comment on notation]
89167
Cardinality of equivalence relations in $\mathbb{N}$
82947
Undecidable cardinality
14972
Cardinality of Vitali sets: countably or uncountably infinite?
5840
divides, not divides and cardinalities
153305
Adding subsets of regular cardinals (Jech p. 226)
3902
Does $k+\aleph_0=\mathfrak{c}$ imply $k=\mathfrak{c}$ without the Axiom of Choice?
132025
Is there an alternative to Cantor's cardinalities that makes proper subsets smaller than their sets?
68230
The cardinality of a countable union of sets with less than continuum cardinality
118390
Symbol for the cardinality of the continuum
98163
Question regarding exponentiation of cardinal numbers
82628
Cardinality of a set of closed intervals
86167
Why are infinite cardinals limit ordinals?