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smooth (of a surface); glassy; velvety; soft
smooth (of an action, proceedings, etc.); fluent (speech); fluid; trouble-free
continuously differentiable
この布は触ると滑らかで気持ちいいです。
This fabric feels smooth and comfortable to touch.
赤ちゃんの肌は生まれつき滑らかで柔らかいです。
My mother's skin has always been smooth.
テーブルの表面が滑らかになりました。
The surface of the table became smooth.