Six — From Proto-Indo-European to English | etymologist.ai
six
/sɪks/·numeral·Old English siex/six attested c. 8th–10th century CE in manuscripts; PIE *swéḱs reconstructed to c. 4500–2500 BCE.·Established
Origin
From PIE *swéḱs, thesame root survives as Greek hex (hexagon), Latin sex (sextet, semester), and in every other IE branch — a numeral so stable it forms the diagnostic core of the comparative method. The Sistine Chapel is etymologically the 'Sixth Chapel'.
Definition
The cardinal number equal to five plus one, descending from Proto-Indo-European *swéḱs through Proto-Germanic *sehs.
The Full Story
Proto-Indo-Europeanc. 4500–2500 BCEwell-attested
The numeral 'six' descends from Proto-Indo-European *swéḱs, one of the best-attested and most securely reconstructed numerals in the entire PIE system. Its reconstruction is considered certainbecause the cognates align with perfect regularity across every branch of the Indo-European family. The *ḱ (palatal velar) in the root is the source of much phonological variation: in satem branches (Indo-Iranian, Slavic
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Englishcontains three separate forms of the PIE numeral *swéḱs — 'six' (Germanic), 'hexa-' (Greek, as in hexagon), and 'sex-' (Latin, as in semester — from Latin sex mēnsis, 'six months'). Andthe Sistine Chapel is named after Pope Sixtus IV, whose title means 'sixth'. Michelangelo painted the ceiling of a PIEnumeral
siex/six. Latin sex (with initial *sw- reduced to *s-) flows directly into Romance languages and into English via learned borrowing (sextet, sextant, semester — from Latin semestris, literally 'six months'). Greek hex (ἕξ) gave the learned prefix hexa- (hexagon, hexameter, hexadecimal). English thus has THREE forms from the same root: six (Germanic), hexa- (Greek), and sex-/sext- (Latin). The Sistine Chapel is named after Pope Sixtus IV — sextus meaning 'sixth' — making the chapel etymologically the 'Sixth Chapel.' Key roots: *swéḱs (Proto-Indo-European: "six — one of the most securely reconstructed numerals in the IE family"), sex (Latin: "six — source of English sextet, sextant, semester, Sistine"), héx (ἕξ) (Ancient Greek: "six — source of English prefix hexa- (hexagon, hexadecimal)"), *sehs (Proto-Germanic: "six — ancestor of Gothic saihs, Old English siex, German sechs").
sex(Latin (true cognate from PIE *swéḱs))héx (ἕξ)(Ancient Greek (true cognate from PIE *swéḱs))ṣáṣ(Sanskrit (true cognate from PIE *swéḱs — satem form))шесть (shest')(Russian (true cognate from PIE *swéḱs))šeši(Lithuanian (true cognate from PIE *swéḱs))sechs(German (true cognate from PIE *swéḱs via Proto-Germanic *sehs))