E·pen·the·sis n.; pl. Epentheses   Gram. The insertion of a letter or a sound in the body of a word; as, the b in “nimble” from AS. nēmol.
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  epenthesis
       n : 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"
       [also: epentheses (pl)]