A lancet is a medical instrument, similar to a scalpel but with a double-edged blade.

A lancet, also called Amphioxus, is a primitive member of the Phylum Chordata in Subphylum Cephalochordata. It superficially resembles a small fish in the shape of the medical instrument (above). They are frequently found buried in sand in warm, tropical waters and reach the size of five centimeters.

The Lancet is a medical journal in the United Kingdom.

In gothic architecture, a lancet is an acutely pointed arch.