People forgive you for a lot of your past indiscretions, but this, they feel, is unforgivable.
The unforgivable java sin of a Pumpkin Spice Latte at Starbucks.
He loathed the neocons who ran the Pentagon, and fiercely opposed the Iraq War as an unforgivable misuse of the American military.
Old English forgiefan "give, grant, allow; forgive," also "to give up" and "to give in marriage;" from for- "completely" + giefan "give" (see give).
The modern sense of "to give up desire or power to punish" is from use of the compound as a Germanic loan-translation of Latin perdonare (cf. Old Saxon fargeban, Dutch vergeven, German vergeben, Gothic fragiban; see pardon). Related: Forgave; forgiven; forgiving.