Spaghetto, confetto, and graffito are the singular forms of spaghetti, confetti, and graffiti.

plate of spaghetti on table, did you know facts
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Although it might sound a little strange, the word for an individual piece of spaghetti is spaghetto. The same goes for a single piece of confetti, which is confetto, as well as a single piece of graffiti, which is graffito, according to Merriam-Webster.