Grass that grows back after hay has been cut, or winter pasture for livestock.
From 'fog' (aftergrowth of grass) + '-age' (a suffix indicating action or result). This is an older agricultural term from Middle English referring to the second growth of grass in a season.
Medieval and early modern farmers depended on foggage to feed their animals through winter—this 'bonus' grass was so valuable that disputes over foggage rights actually went to court!
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