three-square

1 of 2

adjective

: having an equilateral triangular cross section

—used especially of a file

three-square

2 of 2

noun

1

or less commonly three-square rush [so called from the triangular stems] : any of various rushes of the genus Scirpus

especially : chairmaker's rush

2

: a three-square file

Word History

Etymology

Adjective

Middle English thre sqware having three equal sides, from three, thre three + sqware, square square

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