IPA: /ˈbiːmləs/
KK: /ˈbimləs/
Not producing or sending out light; lacking a beam.
The room was beamless, making it feel dark and uninviting.
Beamless → It is formed from "beam" (from Old English "beam", meaning a long piece of timber or a ray of light) and "-less" (meaning without). The word "beamless" means without beams, either in the sense of physical beams of wood or metaphorically, rays of light.
Think of being 'without' ('-less') beams ('beam') — that's why beamless means lacking beams.