Ply Yarn

Some articles on yarns, ply yarn, yarn, ply:

Hand Spinning - Characteristics of Spun Yarns - Plying Methods
... Yarns can be made of two, three, four, or more plies, or may be used as singles without plying ... Two-ply yarn can also be plied from both ends of one long strand of singles using a center-pull ball, where one end feeds from within a ball of yarn while the other end feeds from the outside ... at once without tangling, is another way to ply smaller amounts of yarn ...