xanthomaEnglishOxford Dictionary of Englishxanthoma /zanˈθəʊmə / ▸ noun (plural xanthomas)(plural or xanthomata /zanˈθəʊmətə/) Medicine an irregular yellow patch or nodule on the skin, caused by deposition of lipids. – ORIGIN mid 19th century: from Greek xanthos ‘yellow’ + -oma.