three-square

[ three-skwair ]

adjective

1. having an equilateral triangular cross section, as certain files.

three-square

adjective

1. having a cross section that is an equilateral triangle

   a three-square file

Word History and Origins

Origin of three-square¹

1400–50; late Middle English thre square threefold, modeled on foursquare

Example Sentences

The triangular or three-square form is such a form also as is seldom chosen by any that may make another choise.

From Project Gutenberg

Three-square files are made with equilateral triangular sections, as in Fig. 2223.

From Project Gutenberg