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(old-fashioned, set phrase) sorry to have kept you waiting; used when serving food or greeting someone
「お待ちどおさま」と丁寧に挨拶した。
I politely greeted them saying 'thank you for waiting.'
受付の人がお待ちどおさまと声をかけた。
The receptionist said 'thank you for waiting.'
病院でお待ちどおさまと呼ばれて診察室に入った。
I was called 'thank you for waiting' at the hospital and entered the examination room.