'Pardon' is Latin for 'to give completely' — forgiveness conceived as a total gift with nothing held back.
The action of forgiving or being forgiven for an error or offence; an official release from punishment. As a verb, to forgive or excuse. As an exclamation, used to ask someone to repeat something.
From Old French "pardoner" (to grant, forgive), from Late Latin "perdonāre" (to give wholeheartedly, to remit), a compound of "per-" (through, thoroughly, from PIE *per-, forward, through) + "donāre" (to give, from PIE *deh₃-, to give). The Latin "donāre" also produced "donate," "donation," "donor," and "condone." The prefix "per-" intensifies the act of giving, making "pardon" etymologically a thorough or complete giving-away of punishment. First attested in English
The sale of 'pardons' (papal indulgences remitting punishment for sins) was one of the grievances that sparked the Protestant Reformation. When Martin Luther nailed his 95 Theses to the church door in 1517, he was protesting the idea that divine forgiveness could be bought — that the ultimate 'giving completely' could be reduced to a commercial transaction. Chaucer's 'Pardoner' in The Canterbury Tales is a biting satire of these sellers of forgiveness.