(through Fr. perche from Lat. pertica, a pole or rod used for measurement), a bar or rod used for various purposes, as .e.g. for a navigation mark in shallow waters, for a support on which a bird may rest, or for a pole which joins the back with the fore part of a wagon or other four-wheeled vehicle. As a term of linear measurement, "perch," also "rod" or "pole," =162 ft., 52 yds.; of superficial area, =304 sq. yds.; 160 perches acre. As a stonemason's measure, a "perch" =1 linear perch in length by 12 ft. in breadth and 1 ft. in thickness.