also: むにむざん
noun, noun which may take the genitive case particle 'no'
with all one's might; single-mindedly; headlong
Describes doing something with intense concentration and determination, often rushing into it without distraction. Common in set phrases like 無二無三に～する.
彼は無二無三に仕事に打ち込んだ。
He threw himself into his work single-mindedly.
His intense, single-minded effort paid off.
noun, noun which may take the genitive case particle 'no'
one and only; unique; unparalleled
Rare, somewhat archaic sense meaning something is the only one of its kind. More commonly expressed with 唯一無二 or 無二 today.
この作品は無二無三の傑作だ。
This work is a unique masterpiece.
A yojijukugo combining 無二 (no second) and 無三 (no third), literally 'not two, not three', implying absolute singularity or concentration. The exact historical derivation is uncertain.