Or (short) bkorah {bek-o-raw'}; feminine of bkowr; the firstling of man or beast; abstractly primogeniture -- birthright, firstborn(-ling).
see HEBREW bkowr
H1062. bekorah
בְּכֹרָה noun feminine right of first-born Genesis 25:32; Genesis 23:34 (J) Deuteronomy 21:17; 1 Chronicles 5:1-2, suffix בְּכֹרָתִי Genesis 27:36 (JE); בְּכֹרָתְךָ 25:31 (J); בְּכֹרָתוֺ 25:33; 43:33 (J) 1 Chronicles 5:1.