Lewis & Short

prŏpĭtĭātĭo, ōnis, f. [propitio], an appeasing, atonement, propitiation (post-class.), Macr. Somn. Scip. 1, 7: propitiatio placatio est, Isid. Orig. 15, 4; Ambros. Cant. 2, 14; Vulg. Lev. 23, 28 et saep.
Transf.: ipse est propitiatio pro peccatis nostris, Vulg. 1 Joh. 2, 2.