Abreast \A*breast"\, adv. [Pref. a- + breast.]

1. Side by side, with breasts in a line; as, ``Two men could hardly walk abreast.'' --Macaulay.

2. (Naut.) Side by side; also, opposite; over against; on a line with the vessel's beam; -- with of.

3. Up to a certain level or line; equally advanced; as, to keep abreast of [or with] the present state of science.

4. At the same time; simultaneously. [Obs.]

Abreast therewith began a convocation. --Fuller.

Source: Webster's Revised Unabridged Dictionary (1913)