(1) (Man-made fibres) A nozzle or plate provided with fine holes or slits through which a fibre-forming solution or melt is extruded in the manufacture of man-made fibres.
(2) (Entomology) The small orifices, on the lower lip of the silkworm and at the rear of the abdomen of the spider, through which thread-forming material is extruded in the formation of a cocoon, web or other filamentous structure.
Textile Resource (http://www.textile.org.uk)