An archaic past tense form, possibly of 'guff' or a related verb, meaning to speak foolishly or to bluff in a now-obsolete construction.
Unclear origin; appears to be an irregular past tense form from Middle English, possibly influenced by Germanic verb patterns or simple sound change.
This almost-extinct word shows that English used to have way more irregular verbs (like 'gufought' instead of 'guffed')—most have died out, but fight/fought, think/thought, and buy/bought survive.
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