Synonyms of one by one

Adverb

1. one by one, one after another, one at a time

usage: in single file; "the prisoners came out one by one"

2. by the piece, one by one

usage: one piece at a time; "she sold the plates by the piece"

3. individually, separately, singly, severally, one by one, on an individual basis

usage: apart from others; "taken individually, the rooms were, in fact, square"; "the fine points are treated singly"