From Old English 'bēam' (tree), cognate with German 'Baum' — the meanings 'structural timber' and 'ray of light' both date to Old English.
A long, sturdy piece of timber or metal used in construction; a ray of light.
From Old English 'bēam' meaning 'tree, post, ray of light,' from Proto-Germanic *baumaz (tree). The double meaning of 'structural timber' and 'ray of light' both date to Old English. Key roots: *baumaz (Proto-Germanic: "tree").