(1) Fibrous material made in the woollen trade by pulling down new or old knitted or loosely woven fabric in rag form. (See also mungo and note the distinction.)
(2) Droppings from woollen cards consisting of very short fibres that may be heavily charged with oil and dirt.
Textile Resource (http://www.textile.org.uk)
Wool fibers recovered from either new or used woven or felted cloth and which must be designated as reprocessed or reused. Wool fibers included in this classification usually run .5 in. or more in length.
Textile Links (http://www.textilelinks.com)