adjective.
Growing out abnormally, excessively, or superfluously.
adjective.
Of or relating to epenthesis; epenthetic.
The Century Dictionary and Cyclopedia
Growing out of something else; specifically, abnormally put forth or added; hence, superfluous and incongruous: as, a wart is an excrescent growth on the hand; excrescent knots on a tree; excrescent ornaments on a dress or on a building.
the GNU version of the Collaborative International Dictionary of English
adjective.
Growing out in an abnormal or morbid manner or as a superfluity.
adjective.
a letter which has been added to a root