Plural of 'grater'; kitchen tools with sharp perforations used for shredding or grating foods like cheese or vegetables.
From 'grate' (to scrape) plus the agent suffix '-er' (something that does the action), combined with the plural 's.' The tool was named from its scraping action.
The modern box grater is a relatively recent invention (1800s), but before that people grated food on flat metal surfaces with holes—it's wild that something so common in every kitchen is less than 200 years old as we know it!
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