To search through things in a disorganized way, moving items around to find something.
From Dutch 'ruimen' meaning to clear out or empty. It entered English in the 1500s in the context of searching through cargo on ships, and spread to mean any thorough disorganized search.
The phrase 'rummage sale' started in the 1800s as a way to sell the leftover goods sailors pulled from ship cargo—it literally meant selling the stuff that was 'rummaged' through.
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