Worsted is usually a tightly woven woollen cloth, made from long-staple combed wool yarn. For making flies, doubtless the yarn was mainly used. See also "stuff"
The name comes from the village of Worstead in Norfolk which was a fabric centre of some note. The only difference to ordinary wool is that the fibres have had the crinkle removed.
"Tammy" mentioned in the remarks to the "Brown Shiner", is a worsted cloth (a wool or wool and cotton mix. Worsted means a firm-textured, compactly twisted mainly wool yarn made from long-staple fibers) with a glazed finish. This is chiefly of interest as "shiny" materials of this nature, apart from some wire ribbing, and very occasionally tinsel, ( although this was not widely available)were extremely rare on such flies. This is the closest to a "synthetic" I have seen in such flies. I have two other patterns which specify "tammy" as a body material. The "tammy" could be any color of course, and this would then be specified