'aleph-null' originates from Hebrew, specifically the word 'אֶלֶף' (aleph), where 'aleph' is the first letter of the Hebrew alphabet, and 'null' is derived from the Latin 'nullus', meaning 'none'.

'aleph-null' was introduced by the mathematician Georg Cantor in the late 19th century to denote the smallest infinity in set theory.

Initially, it was used to describe the size of infinite sets, and this meaning has remained consistent in modern mathematical usage.