Definition of preiotation in US English:

preiotation

(also prëiotation, prejotation)

noun

Linguistics
  • The development or occurrence of a palatal glide before a vowel, especially (in Slavonic languages) one having the effect of palatalizing or softening a preceding consonant within the same word.

Origin

Late 19th century; earliest use found in Augustus Henry Keane (1833–1912). From pre- + iota + -ation.