A person who operates or works on a keel (the bottom part of a boat), or someone who loads/unloads boats; also a surname.
From 'keel' (the backbone of a boat, from Old Norse 'kjölr') plus '-er' (one who does). A keeler was a bargeman or boat worker on British rivers and canals.
A keeler was a working-class river or canal boat operator, so the term captures a whole historic working world of transport before railroads—the Keeler Gang was even a notable group of canal workers in Victorian England.
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