first and foremost; above all; most importantly
A set phrase used to emphasize that something is the most important priority or consideration.
First and foremost, health is the most important thing.
Above all, we must ensure safety.
Standard kanji-kana mixed spelling.
Rare variant using the older kanji 先ず for まず.
A fixed phrase composed of 何より (more than anything) + も (emphatic) + まず (first of all).