An Interval Symmetric Set of eight tones with the melodic sequence d c b a b c d e [these variables represent interval sizes]. Octonies are eight-tone Euler Genera.
The term was coined from Latin, but by coincidence, the Anglo-Greek formative element "-octony" has the meaning of "killing" in such terms as tauroctony, the Mithraic bull-slaying ceremony which represents the reordering of the universe by the god Mithras (Ulansey, 1989).
The tonalsoft.com website is almost entirely the work of one person: me, Joe Monzo. Please reward me for my knowledge and effort by choosing your preferred level of financial support. Thank you.