One Who Issues from His Loins/ child/ descendants /offspring
In literary style: a son; his descendant. ("Yarekh" is also a euphemism for the male organ.)
("And all the souls that came from Jacob's loins were seventy souls, and Joseph was in Egypt" - Exodus 1:5; and likewise: "This is the rule: if one comes first in inheritance, his loins' issue come first, and the father comes before all his loins' issue" - Bava Batra 8b)
Translation
Expression (Hebrew)
יוֹצֵא יְרֵכוֹ
Definition (Hebrew)
בִּמְלִיצָה: בְּנוֹ. צֶאֱצָא שֶׁלּוֹ (יָרֵךְ מַשְׁמָע כִּינּוּי לְאֵבֶר הַמִּין הַגַּבְרִי).
("וַיְהִי כָּל נֶפֶשׁ יֹצְאֵי יֶרֶךְ יַעֲקֹב שִׁבְעִים נָפֶשׁ וְיוֹסֵף הָיָה בְמִצְרָיִם"- שְׁמוֹת א ה, וְכֵן:"זֶה הַכְּלָל כָּל הַקּוֹדֵם בַּנַּחֲלָה יוֹצְאֵי יְרֵכוֹ קוֹדְמִין וְהָאָב קוֹדֵם לְכָל יוֹצְאֵי יְרֵכוֹ"- בָּבָא בָּתְרָא ח ב)