the insertion of a vowel or consonant into a word to make its pronunciation easier; "the insertion of a vowel in the plural of the word `bush' is epenthesis"

The insertion of a segment into the middle of a word or morpheme usually with the effect of simplifying articulation; for example, a [b] was inserted into Old English zymel to create the modern word "thimble."

In poetry and phonetics, epenthesis (, from Greek epi "on" + en "in" + thesis "putting") is the insertion of a consonant, a vowel, or a whole syllable into a word, usually to facilitate pronunciation. The deletion of a sound is called elision.