pri·mo·gen·i·ture (pr??m?-j?n??-cho?or?)n.1. The state of being the firstborn or eldest child of the same parents.2. Law The right of the eldest child, especially the eldest son, to inherit the entire estate of one or both parents.[Late Latin pr?m?genit?ra : Latin pr?m?, at first (from pr?mus, first; see per in Indo-European roots) + Latin genit?ra, birth (from genitus, past participle of gignere, to beget; see gen?- in Indo-European roots).]pri?mo·gen?i·tar?y (-j?n??-t?r??), pri?mo·gen?i·tal (-t?l) adj.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.primogeniture (?pra?m???d??n?t??) n1. the state of being a first-born2. (Law) law the right of an eldest son to succeed to the estate of his ancestor to the exclusion of all others. Compare ultimogeniture[C17: from Medieval Latin pr?m?genit?ra birth of a first child, from Latin pr?m? at first + Late Latin genit?ra a birth] primogenitary adjCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014pri?mo?gen?i?ture (?pra? m??d??n ? t??r, -?t???r) n. 1. the state or fact of being the firstborn of children of the same parents. 2. inheritance by the firstborn, specifically the eldest son. [1585?95;