/euh brest"/ , adv. , adj.
1. side by side; beside each other in a line: They walked two abreast down the street.
2. equal to or alongside in progress, attainment, or awareness (usually fol. by of or with ): to keep abreast of scientific developments; keeping abreast with the times.
[ 1590-1600; A- 1 + BREAST ]