τετρακτύς

Ancient Greek

Etymology

τετράς (tetrás) + -τύς (-tús)

Pronunciation

 

Noun

τετρᾰκτῡ́ς (tetraktū́s) f (genitive τετρᾰκτῠ́ος); third declension

Pythagorean name for

  1. the sum of the first four numbers, i.e. 10 (= 1+2+3+4)
    • Carm., Aur. 48:
      ναὶ μὰ τὸν ἁμετέρᾳ ψυχᾷ παραδόντα τετρακτύν, παγὰν ἀενάου φύσεως
      naì mà tòn hametérāi psukhâi paradónta tetraktún, pagàn aenáou phúseōs
    • 160 CE – 210 CE, Sextus Empiricus, Against the Mathematicians 7.94
    • Theo., Sm. p.94.H.
    • Hierocl., in CA 20p.465.M.
  2. the four terms (6:8:9:10) of the proportion corresponding to the chief musical intervals; also their sum +1 (= 36); the sum of the first 8 numbers

Inflection

Further reading

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