double knit

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A jerseylike fabric knitted on a machine equipped with two sets of needles so that a double thickness of fabric is produced in which the two sides of the fabric are interlocked.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A knitted fabric consisting of a double thickness, made on a machine with two sets of needles

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a knit fabric similar to jersey that is made with two sets of needles producing a double thickness joined by interlocking stitches