- Adverb. Informed, well-informed, familiar, acquainted.
- Adverb. Side by side, facing forward, with breasts in a line; as,.
- Adverb. (nautical) Side by side; also, opposite; over against; on a line with the vessel's beam; – with ''of''.
- Adverb. Up to a certain level or line; equally advanced; as, to keep '''abreast''' of [or with] the present state of science.
- Adverb. (obsolete) : At the same time; simultaneously.