Needle

Needle is a term with several related meanings in English. The most common senses refer to slender, pointed tools used to pierce material or guide a thread. A sewing needle is a metal shaft with a sharp point and an eye near the opposite end through which thread is passed. Knitting needles are solid or hollow and come in various diameters; they are used without an eye to form knitted fabric. Medical and surgical needles include a hypodermic needle, a hollow tube used to inject or withdraw fluids, and a suture needle, which carries a thread through tissue to close wounds.

Other important meanings include the compass needle, a magnetized bar that aligns with the Earth's magnetic field and indicates magnetic north, and pine needles, the slender leaves of pine trees and other conifers. These leaves are important for photosynthesis and are often used in botanical identification. The term also extends to devices such as a record player needle, or stylus, which reads grooves on vinyl records.

Materials, design, and safety vary by use. Most ordinary needles are made of steel or stainless steel and are engineered with specific point geometries and, for sewing needles, an eye shaped to accommodate thread. Surgical needles can be curved or straight and may be disposable or reusable. Hypodermic needles require sterile handling, and used needles must be disposed of in approved sharps containers to reduce risk of injury and infection.