Noun

1. A benign or malignant tumour, especially of the gonads, that arises from germ cells and consists of different types of tissue such as skin, hair, or muscle.
   • 1972, Patrick O'Brian, Post Captain:

     ‘What is a teratoma?’ asked Jack, holding the object in his hand. ‘A kind of grenado?’ ‘It is an inward wen, a tumour: we find them, occasionally, in the abdominal cavity. Sometimes they contain long black hair, sometimes a set of teeth: this has both hair and teeth.’