'abeam' originates from the nautical term 'beam,' which refers to the widest part of a ship. The prefix 'a-' indicates 'on' or 'in the direction of.'

'abeam' evolved from the nautical terminology used in the 17th century, where 'beam' was a common reference point for navigation.

Initially, it meant 'on the beam of a ship,' but over time it evolved to mean 'at a right angle to the length of a ship or aircraft.'