墨すみ糸いと

noun

inked marking string; snap line

A string coated with ink, used in carpentry and construction to mark straight lines on wood or other materials. Often used with a sumitsubo (ink pot).

• 大だい工くは墨すみ糸いとを使つかって木もく材ざいに直ちょく線せんを引ひいた。

  The carpenter used an inked marking string to draw a straight line on the lumber.