Other forms: scathing; scathes
To scathe is to obliterate something as if you'd burned it to ashes — or to direct ferocious, fiery disapproval or anger in the direction of a person.
The verb scathe is pretty old-fashioned; these days you're more likely to encounter the adjectives scathing and unscathed. The word derives from a root meaning "to harm or injure," and it was once used in both a literal and figurative way. Long ago, you might have scathed your old love letters by burning them in the fireplace, and then scathed your sister by telling her to get lost when she asked what you were doing.