To shine upon or illuminate with beams of light; or to construct with beams of wood.
From 'em-' (to furnish with or to cause) combined with 'beam,' which comes from Old English 'beam,' originally meaning 'tree' and later 'ray of light' or 'structural support.'
The word 'beam' itself is beautifully ambiguous—it refers to both a wooden support and a ray of light, so 'embeam' can mean both 'to illuminate' and 'to support with beams,' showing how our ancestors saw connections between light and structure.
Complete word intelligence in one call. Free tier — 50 lookups/day.