Let's start with Noil (sometimes spelled Noile). From Fairchild, p. 415, "Short fibers removed during the combing operation of yarn making...the fibers sometimes are mixed with other fibers to make low-quality yarns or are used for purposes other than yarn making, such as padding, stuffing. See BOURETTE SILK." Huh? What is Bourette Silk?
Bourette Silk: "A coarse silk yarn spun from the waste that is produced in the manufacture of SCHAPPE SILK...the yarn is lumpy, irregular, and possesses low elongation. Tufts from the nubs, noils, and other waste are interspersed throughout the yarn..." (Fairchild, p. 71.)
SCHAPPE SILK! WHY?! WILL THE DICTIONARY DIVE NEVER END?!
Essentially, Silk Noil is produced using the waste by-product of filament reels. Even carefully unreeled silk is going to have uneven ends. Those uneven ends are spun into Bourette Silk...or Schappe Silk...or better known as Silk Noil. For some reason, probably because of the nubby slubs in the weaving, Silk Noil is sometimes mistakenly called Raw Silk. Raw Silk has not been cleaned of is sericin. You are closer to raw silk with Organza...or even with Schappe Silk... than you would be with Noil.
Silk Noil is surprisingly soft for a fabric that still has bits of cocoon woven in to it, has easy drape, and works well for tailored blouses, can be gathered, pleated, or tucked at will. However, it is relatively thick compared to other silks, so too much gathering adds bulk. Additionally, as it is the product of waste by-product, Noil is weaker than other silk fabrics. Still stronger than cotton, but not as strong as chiffon, with it's intact filaments.
As for Noil, when I Googled Noil in Fashion History, I found this wonderful blog by Revival Clothing, tracking use as far back as the middle ages. More recently, it has entered fashion lexicon as part of Jedi costume, and Haute Couture. Remember, when looking at the Dolce and Gabbana dress for $532 of silk noil...waste by-product. Couture if a FASCINATING subject. And a strong argument to become a skilled seamstress in your right!