a narrow-bladed chisel for paring and mortising, driven by hand pressure or with a mallet
Word origin
[1680–90; firmer ‹ F fermoir, b. formoir that which forms (deriv. of former to form ‹ L fōrmāre) and fermer to make firm (‹ L firmāre)]This word is first recorded in the period 1680–90. Other words that entered Englishat around the same time include: commercial, gangway, reservoir, skyrocket, turnoff