ex·cres·cence 
(ĭk-skrĕsəns)
(ĭk-skrĕsəns)n.
1. An outgrowth or enlargement, especially an abnormal one, such as a wart.
2. A usually unwanted or unnecessary accretion: "Independent agencies were an excrescence on the Constitution" (Los Angeles Times).
[Middle English, from Latin excrēscentia, from neuter pl. of excrēscēns, excrēscent-, present participle of excrēscere, to grow out : ex-, ex- + crēscere, to grow; see ker-2 in the Appendix of Indo-European roots.]