Yarn consisting of a central thread surrounded by staple fibres. The yarn has the strength and elongation of the central thread whilst exhibiting most of the other characteristics of the surface staple fibres.
Example 1 : A sewing thread consisting of a central synthetic continuous-filament yarn surrounded by cotton fibres.
Example 2 : Worsted yarn with bulked-nylon core, e.g., typically 1/24s worsted count (37 tex) with approximately 33% of nylon. These yarns are normally produced to give strength and elasticity to the fabric.
Example 3 : A spun yarn from either natural or man-made fibres incorporating an elastomeric core, These yarns are normally used in stretch fabrics.
Textile Resource (http://www.textile.org.uk)