sunbeam noun5 •A ray of sunlight; especially, a demarcated, narrow, and intense (relative to ambient light) ray of sunlight (as revealed by, for example, its diffraction among dust particles). •(UK) Synonym of sunshine (“ironic form of address to an inferior or troublemaker”).DOCTOR: You seem to be our best bet so far, don't you think so, Mel? Mel? Where's Mel? DEPUTY: No, no, no, sunbeam. You're coming with us. — 1987 •Any of various lycaenid butterflies of the genus Curetis. •Any hummingbird of the genus Aglaeactis. •(informal, old-fashioned) An item of cutlery or crockery laid out on a table, but not used, and which can be returned to the drawer without being washed. formssunbeams