What pasta is described as a very thin spaghetti on Wikipedia’s spaghetti page? Capellini.
Capellini is a long, delicate pasta made in thin strands, closely resembling spaghetti but with a smaller diameter. The name comes from Italian capelli, meaning “hair,” and it is sometimes translated as “little hairs.” Because it cooks quickly and has a fragile texture, capellini is best paired with light sauces, seafood, vegetables, or broth rather than heavy sauces.
Capellini is often confused with capelli d’angelo, or angel hair. Angel hair is generally even thinner, although everyday labels and commercial pasta products sometimes blur the distinction. Spaghettini is another related pasta, but it is a thinner version of standard spaghetti rather than a synonym for capellini.
The word spaghetti refers broadly to long, solid, cylindrical pasta. Related forms include spaghettoni, which is thicker, and spaghettini, which is thinner. Capellini belongs to this family of thin strand pastas but is treated as its own named variety.