What does aleph mean?
Aleph is the first letter of the Hebrew alphabet, written א and representing a glottal stop consonant. In English usage it appears chiefly in two settings: Jewish and Hebrew studies, where learners encounter it as the opening letter of the alphabet, and mathematics, where the German-born mathematician Georg Cantor adopted the symbol ℵ to label the sizes of infinite sets — aleph-null being the countable infinity of the natural numbers, followed by larger alephs such as aleph-one. The word's historical reach is remarkable: Hebrew aleph descends from the Phoenician letter of the same name, which also gave rise to the Greek alpha, and thus indirectly to the very word 'alphabet'. Though scholarly in register, aleph carries rich cultural resonance, symbolizing beginnings, unity, and the infinite across religion, literature, and science.
The first letter (א) of the Hebrew alphabet, representing a glottal stop.
"Every Torah scroll begins its text with the second aleph of Genesis."
In Hebrew, aleph is silent on its own and takes its sound from an accompanying vowel.
In mathematics, any of the transfinite cardinal numbers denoted by the symbol ℵ, beginning with aleph-null (ℵ₀), the cardinality of the natural numbers.
"The continuum hypothesis asks whether there is a set whose size lies strictly between aleph-null and that of the real numbers."
This sense is confined to set theory and mathematical logic.
The plural is rare outside mathematical contexts, where one may speak of the sequence of aleph numbers.
"Cantor's hierarchy of alephs extends without end."
The very word 'alphabet' exists because of aleph — Greek took 'alpha' from it and fused it with 'beta', naming an entire concept after this single letter.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of aleph
Aleph comes from the ancient West Semitic letter ʾālep, meaning 'ox', whose pictographic ox-head shape was passed down through the Phoenician alphabet. The Greeks borrowed this letter as alpha, and the pairing of alpha and beta gave us the word 'alphabet' itself. The same ancestral letter survives today as Hebrew aleph and Arabic alif, making these three scripts siblings of a common origin.
Word family
Usage notes
Outside of Hebrew language study and Jewish religious contexts, 'aleph' appears mainly in mathematical writing on set theory, where the aleph numbers are standard notation for infinite cardinalities. It carries no informal register and is essentially a technical or scholarly term in English.
Don't confuse with
Alpha is the first letter of the Greek alphabet, whereas aleph is the first letter of the Hebrew alphabet, though both descend from the same Phoenician ancestor.
Alif is the first letter of the Arabic alphabet, a sister form of aleph rather than the same letter.