An Etymological Dictionary of Astronomy and Astrophysics

1. A collection of nearly parallel → light  → rays or a concentrated stream of → particles. See also → beam of light.
   

2. The area of the sky being observed at any one time by a → radio telescope.
   

3. The size of the → diffraction pattern; synonymous with point spread function.

Etymology (EN): M.E. beem, from O.E. beam “tree;” akin to O.H.G boum “tree,” Ger. Baum.

Etymology (PE): Tâbé, from tâb; tâbidan “light; to shine”

• -é noun suffix.