twined: of thread, twisted together from several strands into one strong, fine thread
This word describes a step in making thread. Several separate strands were twisted around one another into a single ply, which produced a thread that was stronger, smoother, and more even than any one strand alone. English Bibles usually render the result as "fine twined linen" or "finely twisted linen."
Every time it appears, it is describing the materials of the tabernacle and the priest's garments: the linen curtains, the screen at the courtyard gate, the ephod, the breastpiece, the sash. It is almost always paired with the word for fine linen, and sometimes with the blue, purple, and scarlet wool, marking those as top-quality worked thread.
Because it only ever turns up in these building accounts, and only in a passive form ("having been twined"), it works less like an everyday verb and more like a technical craftsman's label. It is a close companion to spinning (טָוָה): spinning draws loose fibers into a single thread, and twining then twists finished threads together into one.