Other forms: sunbeams
A sunbeam is a single ray of light from the sun. A sunbeam through the window.
You only see one where there is dust or mist for it to light, which is why they appear indoors. A sunbeam through a gap in cloud has a name of its own in painting.
1nounsunbeamA single ray of light from the sun.
“One sunbeam crossed the whole room at about four o'clock.”
sunbeam is a ray.
Old English sunnebeam is sun plus beam, and beam once meant a tree or a beam of wood.
Old English
sunnbēam
Middle English
sonnebem
English, today
sunbeam
Built from
From Middle English sonnebem, sonnebeem, from Old English sunnbēam, sunnebēam (“sunbeam”), equivalent to sun + beam.
Etymology from Wiktionary, CC BY-SA