abreast
adj.next to someone or something else, especially when you are moving at the same speed. It is often used when talking about ships or people walking together.
adj.situated next to or alongside another person or object, typically at the same level or speed. Often used in nautical contexts to describe the relative position of vessels.
“The two ships sailed abreast of each other.”
“The two friends walked abreast through the park, sharing a quiet conversation about their upcoming trip.”
“The fleet maintained a formation where each vessel remained abreast of its neighbors, ensuring that no ship fell behind during the high-speed crossing of the strait.”
“Heading into the summer, Arsenal were keeping abreast of Guimaraes' situation at Newcastle , although others were considered a higher priority.”
From Middle English abrest. By surface analysis, a- (“on, at”) + breast, meaning “breasts (chests) in line, side-by-side and exactly equally advanced”; roughly “breast-by-breast”.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.