A young or small cymbal, or a dialectal or archaic variant of cymbal or cymbling (a type of squash).
Either from cymbal + -in (diminutive suffix), or from Dutch/German zucchini-related words. The squash meaning likely comes through European linguistic borrowing.
This is one of those words that slipped between languages—different regions used different names for the same vegetable, and 'cymblin' represents how plant names got wonderfully tangled as they traveled trade routes!
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