opened or separated something by pulling down the zipper; also means to reveal or expose something that was hidden.
From 'un-' (prefix meaning to reverse) + 'zip' (from the sound zippers make), popularized in the 1920s-30s. The word combines the imitative sound of a zipper closing with the prefix for reversal.
The word 'zip' is pure onomatopoeia—someone literally named it after the sound it makes! Before zippers were invented in the late 1800s, people had no word for this action, showing how technology creates our language.
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