From Old French grater 'to scrape,' from Frankish *krattōn 'to scratch' — the same root behind 'graffiti.'
A kitchen device with a rough surface used for shredding food into small pieces.
From Middle English grater, from Old French grateor, from grater 'to scrape,' from Frankish *krattōn 'to scratch,' from Proto-Germanic *krattōną. The Germanic root produced a family of scratching/scraping words across several languages. Key roots: *krattōną (Proto-Germanic: "to scratch").
The same Frankish root that gave French gratter 'to scratch' also gave us 'graffiti' via Italian — graffiti are literally 'scratchings,' from Italian graffiare 'to scratch,' from the same Germanic source.