adv at the same time; simultaneously.
2. abreast ·adv side by side, with breasts in a line; as, "two men could hardly walk abreast.".
3. abreast ·adv side by side; also, opposite; over against; on a line with the vessel's beam;
with of.
4. abreast ·adv up to a certain level or line; equally advanced; as, to keep abreast of the present state of science.