1. Na-adjective (keiyodoshi), Noun

   big; large; drastic; substantial

   この政策で物価は大幅に値上がりした。

2. Noun

   full-width cloth (approx. 72 cm wide for traditional Japanese clothing; approx. 140 cm wide for Western clothing)

   see 小幅see 中幅

Also written 大巾【おおはば】oohaba