Long, narrow strips of paper or ribbon used as decorations, or in nature, flowing bands of light (like the aurora borealis).
From 'stream' (flowing water, from Old English 'streám') plus agent suffix '-er' and plural '-s.' Originally described actual streams of water before extending to mean ribbon-like decorations.
In physics, 'streamers' also refers to the branching electrical discharges in lightning and plasma—they're called that because they flow and branch like streams of water.
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