How do you spell Abreast

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