1) The first letter of the Hebrew alphabet (ℵ).
2) A → cardinal number
representing an uncountable set. For example,
ℵ0 (pronounced aleph-null, aleph-nought, or
aleph-zero) is the smallest infinite cardinal and
ℵ1 is the smallest cadinal larger than ℵ0.
Hebrew and Phoenician letter, from Semitic languages.