磨とが

とが · toga

JLPT N1 verb 未然形

磨が is the negative stem of 磨ぐ — to sharpen, to hone, to whet, to grind.

How it’s built

磨ぐ磨が

Negative stem (未然形). Never used alone — it is the base for ない (not), れる/られる (passive), せる/させる (causative): 書か → 書かない.

磨ぐ is a godan verb (u-verb), so it follows that pattern.