ℵ

Etymology
Introduced by Georg Cantor, based on the letter, initial letter of אינסוף (infinity).

Symbol

 * 1)  Symbol for the transfinite enumeration of the infinite cardinal numbers in order of magnitude, a function mapping ordinal numbers to infinite cardinals.

Usage notes
Unicode has two code points for the Hebrew letter aleph. For normal Hebrew text, U+05D0 should be used. U+2135 should be used for the mathematical symbol in Latin-script text because it will share the left-to-right direction of that text.