Frough is provincial in the north of England, and means anything loose, spongy, or easily broken; often applied to wood, as brittle is to mineral substances.--Brockett's Glossary. 'Froughy butter,' is rancid butter.
The latter of these words is in common use in many parts of New England. It is doubtless a corruption of frough, which is sometimes used here.--Pickering.