certain cure; guaranteed remedy
Refers to a treatment or method that is guaranteed to cure a disease or solve a problem. Often used in medical or figurative contexts.
この薬は風邪の必治薬と言われている。
This medicine is said to be a sure cure for colds.
彼のアドバイスは悩みの必治策だった。
His advice was a guaranteed remedy for my worries.
sure-cure medicine; guaranteed remedy
Compound of 必 (certainly) and 治 (cure/heal). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning of a guaranteed cure.