Definition - Inserting a consonant, vowel, or syllable into a word to make it easier to pronounce.

Example -

(1) The name Dwight becomes Du-wight and
(2) the word mischievous becomes mis – chee – vee – ous.

Etymology -
The word derives from the Greek epi, on + en, in + thesis, putting.

Oxford English Dictionary -
Its first citation is from 1657:
"Epenthesis is the interposition of a letter or syllable in the midst of a word."
(J. Smith Myst. Rhet. 171)

Please comment