noun
aftereffect; after effect
Refers to a lingering effect or consequence, often used in medical, scientific, or formal contexts.
薬の余効で眠気が続いた。
I felt drowsy as an aftereffect of the medicine.
地震の余効として、地盤沈下が観測された。
Land subsidence was observed as an aftereffect of the earthquake.
Compound of 余 (yo, 'remaining') and 効 (kō, 'effect').