Polaroid

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1930s: from polarize + -oid.

wiktionary

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Genericization of the trademark Polaroid, owned by Polaroid Corporation.

etymonline

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Polaroid (n.)

material which in thin sheets produces a high degree of plane polarization of light passing through it, 1936, proprietary name (Sheet Polarizer Co., Union City, N.J.). As a type of camera producing prints rapidly, it is attested from 1961.