Tarnation
Origin
From darnation, influenced by tarnal (from "eternal"), from (euphemistic) damnation; see darn.
Full definition of tarnation
Noun
tarnation
(countable and uncountable; plural tarnations)- (archaic) The act or process of damnation or reprobation; hell.What in tarnation is going on?
Usage notes
This New Englandism has fallen out of use in New England, but is remembered for its colorfulness and is still used in the Southeastern United States as a minced oath, where ‘hell’ or ‘damn’ would otherwise be said, especially in the phrase "what in tarnation".