also: ゆうやく · ゆう
noun
A vitreous coating applied to ceramics, pottery, or metalwork, fused by firing. In everyday contexts, うわぐすり is the most common reading; ゆうやく and ゆう are technical.
この茶碗の釉薬は美しい青緑色だ。
The glaze on this tea bowl is a beautiful blue-green.
陶芸家は釉薬をかける前に素焼きをする。
The potter bisque-fires the piece before applying the glaze.