having a cross section that is an equilateral triangle
a three-square file
three-square in American English
(ˈθriˈskwɛr)
adjective
forming an equilateral triangle in cross section, as a three-cornered file
three-square in American English
(ˈθriˈskwɛər)
adjective
having an equilateral triangular cross section, as certain files
Word origin
[1400–50; late ME thre square threefold, modeled on foursquare]This word is first recorded in the period 1400–50. Other words that entered Englishat around the same time include: mature, oblique, peg, structure, transit