adv. - Side by side, with breasts in a line; as, "Two men could hardly walk abreast."
adv. - Side by side; also, opposite; over against; on a line with the vessel's beam; -- with of.
adv. - Up to a certain level or line; equally advanced; as, to keep abreast of [or with] the present state of science.
adv. - At the same time; simultaneously.