- one by one, one after another, one at a time - in single file; "the prisoners came out one by one"
- by the piece, one by one - one piece at a time; "she sold the plates by the piece"
- individually, separately, singly, severally, one by one, on an individual basis - apart from others; "taken individually, the rooms were, in fact, square"; "the fine points are treated singly"