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porphyrogenite

British  
/ ˌpɔːfəˈrɒdʒɪˌnaɪt /

noun

  1. (sometimes capital) a prince born after his father has succeeded to the throne

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of porphyrogenite

C17: via Medieval Latin from Late Greek porphurogenētos born in the purple, from Greek porphuros purple