• synonyms


  1. having an equilateral triangular cross section, as certain files.
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Origin of three-square

1400–50; late Middle English thre square threefold, modeled on foursquare
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for three-square

Historical Examples

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

    Modern Machine-Shop Practice, Volumes I and II

    Joshua Rose

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

British Dictionary definitions for three-square


  1. having a cross section that is an equilateral trianglea three-square file
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Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012