"act of pardoning a wrong act," 1620s, from Latin condonationem (nominative condonatio) "a giving away," noun of action from past-participle stem of condonare "to give up, remit, permit," from assimilated form of com-, here probably an intensive prefix (see con-), + donare "give as a gift" (from donum "gift," from PIE root *do- "to give").
Condonation is the remission of a matrimonial offence known to the remitting party to have been committed by the other; on the condition subsequent that ever afterward the party remitting shall be treated by the other with conjugal kindness. [Joel Prentiss Bishop, "Commentaries on the Law of Marriage and Divorce," 1864]