Moving or proceeding without problems or obstacles; smooth and seamless. Often used adverbially as 'smoothly'.
会議は予定どおりスムーズに進行した。
The meeting proceeded smoothly as scheduled.
新しいシステムのおかげで業務がスムーズになった。
Thanks to the new system, operations became smoother.
彼の説明は分かりやすく、話がスムーズに進んだ。
His explanation was easy to understand, and the discussion went smoothly.