资料来源 : Webster's Revised Unabridged Dictionary (1913)

Porphyrogenitism \Por`phy*ro*gen"i*tism\, n. [LL. porphyro
   genitus, fr. Gr. ?; ? purple + root of ? to be born.]
   The principle of succession in royal families, especially
   among the Eastern Roman emperors, by which a younger son, if
   born after the accession of his father to the throne, was
   preferred to an elder son who was not so born. --Sir T.
   Palgrave.