A one-room or studio apartment where the living and kitchen areas are not separated; typically a small layout for single occupancy.
大学進学を機に都内でワンルームを借りた。
When I went to university I rented a one-room apartment in the city.
ワンルームは家賃が安いが収納が少ないことが多い。
One-room apartments are cheap but often have little storage.
友人が引っ越してワンルームで一人暮らしを始めた。
My friend moved and started living alone in a one-room apartment.