A dialect term, possibly referring to a gatherer or someone who collects things, or a variant of words relating to pike fish.
Possibly from 'gedd' (pike) with an agent suffix '-er', or from a separate Germanic root related to gathering or assembling, but etymology is uncertain in dialectal terms.
Some old dialect words are so obscure that their origins are genuinely mysterious—'gedder' might be a lost piece of vocabulary that existed in just a few villages before people stopped using it!
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