aleph

n.the 1st letter of the Hebrew alphabet

1. In Hebrew, the first letter of the alphabet is aleph.
   在希伯来语中，字母表的第一个字母是阿列夫。
2. Aleph is often used in set theory to denote cardinal numbers of infinite sets.
   阿列夫常用于集合论中表示无限集合的基数。