Spinneret

silk-spinning organ of a spider or the larva of an insect

A spinneret is the part of a spider's body that makes its silk. Spiders have one, two, or three pairs of spinnerets. The spinnerets are usually close together.

Drawing of the gland inside a spinneret.
The spinnerets of this Agelenopsis spider are easy to see.
The spinnerets of this Argiope aurantia spiral web weaver are very small and are close to its body.