Simple past tense and past participle of burrow.(verb)
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Use "burrowed" in a sentence
"* hop, hop* It's the first in a trilogy, the last of which I've read (burrowed from the library)."
"Sherrod was a crazy racist radical who had "burrowed" her way into the Obama administration to radiate "reverse-racism" throughout the land from her obscure position at the U.S. Department of Agriculture."
"Journalist Seymour Hersh tells Terry Gross that Cheney probably has spies/servants 'burrowed' into government positions and working for him."