The first letter of Proto-Canaanite and its descendant Semitic alphabets

• Name of the Hebrew letter aleph א and Arabic alif ا

原始迦南字母及其后裔闪族文字的第一个字母

• 尤指希伯来文 א 与阿拉伯文 ا

In set theory, the cardinality of an infinite well-ordered set

• Written with the symbol ℵ and subscripts, e.g., ℵ0

集合论中，良序无限集合的基数

• 亦指枚举无限基数的阿列夫数 ℵα