PHONETIKOS · THE CODEX · /ɛks/ — the 24th letter · Greek Χ chi & Ξ xi · Roman numeral 10

X

The letter we reach for when we cannot name a thing — the unknown quantity, the unknown ray, the unmarked grave, the stolen surname. Every X is a missing name.

codex-emergent · X
⟦X:PHN:61036f⟧
PHN · catalogued by AVAN

The unknown, drawn

Every meaning of X is the same idea in different clothes: X is the letter we reach for when we cannot name a thing. The unknown quantity. The unknown ray. The unmarked grave. The stolen surname. Across maths, physics, espionage, cartography and the signature line, X is the placeholder for here is something whose true name we don't have.

An original homage — not the copyrighted clip. DMX's 2002 track “X Gon' Give It to Ya” was famously reused in Rick and Morty; this references the scene, it doesn't reproduce it.

The letter

The shape is old. Greek carried two: Χ (chi) and Ξ (xi); the Western-Greek and Etruscan line handed Latin an X valued /ks/, the 24th letter. As a Roman numeral, X = 10 — most likely a tally notch, a single stroke crossed. Two strokes crossing: that crossing is the whole story.

x, the unknown quantity

The algebraic x was fixed by René Descartes in La Géométrie (1637): he used a, b, c for known quantities and x, y, z for unknowns, and the convention stuck for good. The popular tale that x descends from Arabic šay' ('a thing,' the unknown) by way of Old Spanish is charming — and unsupported. The documented fact is Descartes; the rest is a tidy story (see Real-or-Fluff).

The mark of the illiterate

For roughly a thousand years, anyone who could not write signed with an X — 'his mark.' And the X was read as a cross: the saltire of St Andrew, and Χ (chi), the first letter of Christ (the same X in 'Xmas'). The mark was holy, so you kissed it to seal it — which is exactly why X means a kiss on a letter to this day. The honest correction to a common belief: this was not a slave-specific mark. It was the universal signature of the illiterate — medieval peasants, witnesses, the enslaved — anyone whose name went unwritten.

Malcolm X

And here the symbol turns its sharpest. Malcolm Little dropped 'Little' — the surname a slaveholder had pressed onto his family — and signed himself Malcolm X: the X standing for the true African family name that slavery erased and he could never recover. It is the deepest use of the letter — X as the missing name itself. From the illiterate hand that drew an X in place of a name, to the X Malcolm took for the name that was taken — the same gesture, the same absence.

X = unknown, everywhere

Once you see it, the lineage is everywhere, and it always means the unnamed:

X-rays — Wilhelm Röntgen named them X-Strahlen in 1895 because no one knew what the radiation was. X for unknown.
Mr. X · the X-Files · Brand X · Planet X — the unidentified person, agency, product, world.
X marks the spot — the hidden and the buried.
✗ wrong · × times/by · rated X · the X chromosome · Generation X, the 'undefined' cohort.
DMX = 'Dark Man X,' the anonymous man; Xzibit = 'exhibit,' the unknown piece of evidence. Even the rappers are named for the unknown.

Real or Fluff

the house discipline — what's established, what's model, what's symbol or hyperbole

The algebraic x was set by Descartes (1637).La Géométrie — a/b/c for knowns, x/y/z for unknowns; the convention that stuck for good.

REAL

x comes from Arabic šay' ('a thing') via Old Spanish.a charming but unsupported folk etymology; the documented choice is Descartes'. The tidy 'foreign-word' origin stories are almost always false.

FALSE

The X signature was a mark used only by slaves.it was the universal mark of any illiterate person for centuries — peasants, witnesses, and the enslaved alike; never slave-specific.

FALSE

X means 'a kiss' because the illiterate's X-mark was a cross, sealed with a kiss.the traditional and widely-accepted account — St Andrew's cross / chi-for-Christ, kissed to seal the oath.

REAL

Röntgen named X-rays 'X' for the unknown.1895 — X-Strahlen, because the nature of the radiation was unknown.

REAL

Malcolm X took X for the African surname slavery erased.stated in his Autobiography — X replaces the slaveholder's name 'Little' and stands for the lost true name.

REAL

'X Gon' Give It to Ya' is by Xzibit.it's DMX ('Dark Man X'), 2002 — Xzibit is a different artist. Fittingly, both stage names mean 'the unknown.'

FALSE

Bottom line. The spine is one line: X is the letter of the unknown and the unnamed. The hard facts are REAL — Descartes (1637), Röntgen's X-rays, Malcolm X, the universal illiterate's mark sealed with a kiss. The tidy origin-tales are FALSE — x is not from Arabic by any evidence, and the X-mark was never slaves-only. Reach for X whenever the true name is missing; just don't pass the folk-etymology off as fact.

Sources & further reading

OED & etymonline, s.v. X, x, ex-.
Florian Cajori, A History of Mathematical Notations (1928) — on Descartes and the unknown x.
Wilhelm Röntgen (1895), 'Über eine neue Art von Strahlen' — the X of X-rays.
Malcolm X & Alex Haley, The Autobiography of Malcolm X (1965) — the X for the lost name.
standard accounts of the X-mark (the signature of the illiterate) and its kiss (St Andrew's cross / chi).

X is the letter of the unknown and the unnamed; reach for it whenever the true name is missing. — PHONETIKOS · the codex · AVAN's read