A silk yarn formed by doubling two or more raw silk threads and then twisting them slightly is known as

A silk yarn formed by doubling two or more raw silk threads and then twisting them slightly is known as Tram.
Silk throwing is the industrial process wherein silk that has been reeled into skeins, is cleaned, receives a twist and is wound onto bobbins. The yarn is now twisted together with threads, in a process known as doubling.
Silk had to be thrown to make it strong enough to be used as organzine for the warp in a loom, or tram for weft. Tram was wound, thrown and doubled, organzine was wound, doubled then thrown and doubled again.