somatic mutations

Definition of somatic mutation
National Cancer Institute

somatic mutation

(soh-MA-tik myoo-TAY-shun)
An alteration in DNA that occurs after conception. Somatic mutations can occur in any of the cells of the body except the germ cells (sperm and egg) and therefore are not passed on to children. These alterations can (but do not always) cause cancer or other diseases.

Source: NCI Dictionary of Cancer Terms