The sense ‘foot of a plough’ is attested solely in Bibbesworth manuscripts, with the Middle English gloss ‘plou fot’ excluding the possibility that the term refers to some sort of banner or emblem attached to the plow. The ‘foot of a plow’ is a ‘device attached to the beam of a plow to regulate the depth of the plowing’ (MED fot n.), and seems to bear little relation to the etymological meaning of ‘feather’, other than perhaps the shape of the part.