also: ここんぶそう
expression
unparalleled in history; matchless through all ages
A yojijukugo used to describe someone or something that has no equal in all of history. Often found in literary or rhetorical contexts.
彼の功績は古今無双と称えられた。
His achievements were praised as unparalleled in history.
古今無双の名刀が展示されている。
A matchless sword, unrivaled through the ages, is on display.
天下無双 means 'unrivaled under heaven' (in the whole world), while 古今無双 emphasizes being unmatched across all of history.
A yojijukugo composed of 古今 (ancient and modern, i.e., all ages) and 無双 (unparalleled). The exact origin is uncertain, but it follows a common four-character pattern for expressing supreme uniqueness.