Covered with or obscured by a thin film or layer of something.
From 'be-' plus 'filmed', the past tense of 'film'. While 'film' in the movie sense is modern, 'film' meaning a thin layer or membrane dates to Middle English, possibly from Old English 'filmen'. The 'be-' prefix suggests being thoroughly covered.
What's fascinating is that 'film' originally meant a thin skin or membrane (like the membrane over an egg), and only in the 20th century did it come to mean cinema—the word was repurposed because movie film was literally a thin transparent material, making the connection literal and beautiful.
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