丁てい字じ定じょう規ぎ

noun

T square

A drafting tool shaped like the letter T, used for drawing horizontal lines and as a guide for triangles.

• 製せい図ず台だいに丁てい字じ定じょう規ぎを当あてて水すい平へい線せんを引ひく。

  I draw a horizontal line by placing a T square against the drafting board.