One by one; one at a time.

Apart from others:
— The fine points are treated singly.

synonyms: individually, on an individual basis, one by one, separately, severally.

Roget 87: singly etc. adj.; alone, by itself, per se, only, apart, in the singular number, in the abstract; one by one, one at a time; simply; one and a half, sesqui-^†.    ... show more