A long, thin strand of cotton, nylon, or other fibers used in sewing or weaving. A thing resembling a thread in length or thinness, in particular. A group of linked messages posted on an Internet forum that share a common subject or theme. A helical ridge on the outside of a screw, bolt, etc., or on the inside of a cylindrical hole, to allow two parts to be screwed together. Pass a thread through the eye of (a needle) or through the needle and guides of (a sewing machine). Cut a screw thread in or on (a hole, screw, or other object).