Refers to a remaining trace or mark left behind, often physical or metaphorical. Can be used for scars, ruins, or lingering effects.
戦争の残痕が今も街に残っている。
Vestiges of the war still remain in the town.
その傷は深い残痕を残した。
The wound left a deep scar.
Compound of 残 (ざん, 'remain') and 痕 (こん, 'mark/trace'). The exact historical derivation is uncertain, but the kanji components directly reflect the meaning.