He grew his head
By metaphor: He showed initiative, understanding, and acted beyond the expected or prescribed limit.
(Modern Hebrew)
Translation
Expression (Hebrew)
הִגְדִּיל רֹאשׁ
Definition (Hebrew)
בְּהַשְׁאָלָה: גִּלָּה יוֹזְמָהּ וַהֲבָנָה וּפָעַל מֵעֵבֶר לַמְּצֻפֶּה מִמֶּנּוּ.
(הָעִבְרִית הַחֲדָשָׁה)