The citation from Building (accounts for St. Stephen’s Chapel at Westminster) may also be interpreted as Middle English, but provides an attestation (1331) which predates the earliest English use by two centuries (1532).

The sense ‘thumb’ is not attested elsewhere, but a metonymic interpretation of the thumb as a ‘polisher’ does not seem out of the question. Alternatively, the word may be a corruption of the Latin etymon for thumb, pollex.