A nock is a recess into the end of an arrow or at the tip of a bow. The term is also applied to a structure that covers a section of an artefact and performs the same function, such as the horn nocks of the medieval longbow.
Nocks in arrows are termed self nocks if they are cut directly into the end of the shaft or stele. At times they may have also had a sliver of horn inserted into the end (crosswise to the nock) to act as a reinforcement to the shaft. Bronze nocks are known from Viking Hedeby but they are not common and thought to be possible the hunting arrows of a rich individual and should be thought typical.