Nock

[nok] /nɒk/

noun
1.
a metal or plastic piece at the end of an arrow, having a notch for the bowstring.
2.
a notch or groove at the end of an arrow into which the bowstring fits.
3.
a notch or groove at each end of a bow, to hold the bowstring in place.
4.
Nautical. (def 6a).
verb (used with object)
5.
to furnish with a nock.
6.
to adjust (the arrow) to the bowstring, in readiness to shoot.
/nɒk/
noun
1.
a notch on an arrow that fits on the bowstring
2.
either of the grooves at each end of a bow that hold the bowstring
verb (transitive)
3.
to fit (an arrow) on a bowstring
4.
to put a groove or notch in (a bow or arrow)
n.

“notch on a bow,” late 14c., of uncertain origin, probably from a Scandinavian source (cf. Swedish nock “notch”), but cf. also Low German nokk, Dutch nok “tip of a sail.” Perhaps connected to nook.
v.

“fit (an arrow) to a bowstring,” 1510s, from nock (n.). Related: Nocked; nocking.