n.1 expiation; reparation for a wrong or injury.
2 the reconciliation of God and man.
Phrases and idioms:
the Atonement the expiation by Christ of mankind's sin. Day of Atonement the most solemn religious fast of the Jewish year, eight days after the Jewish New Year.
Etymology: at one + -MENT, after med.L adunamentum and earlier onement f. obs. one (v.) unite