A castrated ram or a playful, mischievous person, used in dialect.
Possibly from Middle English 'gam' (leg, game, or trick) plus a diminutive suffix; related to gammer and dialectal usage.
Some old dialect words are so obscure that they're nearly extinct—gammerel is one that survived in small communities, showing how language preserves the specific concerns and humor of people living close to sheep and farming.
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