Epenthesis is the insertion of a sound which facilitates pronunciation, such as that of b in Fr.
"The Romance of Names" by Ernest Weekley
Throughout the eastern districts there is a strong tendency to epenthesis, e.g.
"Encyclopaedia Britannica, 11th Edition, Volume 3, Slice 5" by Various
The presence of [+optional] segments arising from the unapplication of epenthesis and deletion rules slightly complicates the algorithm given earlier for rule unapplication, in that such segments may optionally be passed over when checking rule environments.
Parsing Using Linearly Ordered Phonological Rules