ham·ar·to·ma 
(hăm′ăr′tōmə)
(hăm′ăr′tōmə)n.
A benign tumor composed of an abnormal mixture of normal tissue elements that develop and grow at the same rate as adjacent tissue, resulting from faulty development in an organ.
[German Hamartom, Greek hamartanein, to miss the mark, go wrong, German -om, -oma.]
ham′ar′toma·tous (-tŏmə-təs, -tōmə-təs) adj.