noun, noun, used as a suffix, counter
unit of cloth width (approx. 30–38 cm)
Traditional unit for measuring cloth breadth, used after numbers in the hito-, futa-, mi- counting system. One 幅 is roughly the width of a bolt of kimono fabric, about 30–38 cm.
一反の布は、幅が約ひと幅（約36センチ）です。
One tan of cloth is about one no (about 36 cm) wide.
この着物の生地は、ふた幅使って仕立てられています。
This kimono fabric is tailored using two no widths.
反 is a unit of cloth length (about 10.6 m), while 幅 is a unit of cloth width.
The reading の is native Japanese, and the kanji 幅 (width) is used for this traditional cloth measurement. The alternate kanji 布 (cloth) directly reflects the material measured.