Definition of octonion in US English:

octonion

(also octonian)

noun

Mathematics
  • A type of hypercomplex number with eight coefficients, having the form x = x0 + x1e1 + x2e2 + x3e3 + x4e4 + x5e5 + x6e6 + x7e7, where the xn are real numbers and the en are imaginary units which, in conjunction with 1 and −1, form a closed, non-commutative, non-associative system under multiplication.

Origin

Late 19th century (in an earlier sense). From classical Latin octōnī eight each, eight at a time + -ion, after quaternion.

Pronunciation

octonion

/ɒkˈtəʊnɪən/