ectomy: From the Greek ôekö (out) + ôtomeö (a cutting) = a cutting out. The surgical removal of something. For example, a lumpectomy is the surgical excision of a lump which may be benign or not, tonsillectomy is the removal of the tonsils, a partial colectomy is removal of part of the colon, an appendectomy is removal of the appendex, etc.