in Geometry, a quadrilateral figure both equilateral and equangular. See Geometry.

SQUARE-Roof. See Algebra and Arithmetic, No. 33, and 34.

Hollow SQUARE, in the military art, a body of foot drawn. drawn up with an empty space in the middle, for the colours, drums, and baggage, faced and covered by the pikes every way to keep off the horse.

Square, among Mechanic, an instrument consisting of two rules or branches, fastened perpendicularly at one end of their extremities, so as to form a right angle. It is of great use in the description and mensuration of right angles, and laying down perpendiculars.

T Square, or Tee Square, an instrument used in drawing, so called from its resemblance to the capital letter T.