syntonism--prophetes.ai

syntonism Electr.
  (ˈsɪntənɪz(ə)m)
  [f. Gr. σύν syn-¹ + τόνος tone + -ism.]
  = syntony 1.

1903 Rep. Brit. Assoc. Adv. Sci. 761 The question of ‘syntonism’, by which it is proposed to assure the secrecy of messages.

Oxford English Dictionary