spur

Spur is a term used across disciplines to denote a short projection, branch, or auxiliary line that extends from a main body. Spurs can be natural or man-made and are defined by their function as a projection that increases reach, contact, or connectivity in a system.

In botany, a nectar spur is a tubular extension of a petal or sepal that typically contains nectar. The spur often influences pollination by guiding pollinators to the nectar and the reproductive organs.

In anatomy and zoology, spurs are projections on limbs or digits of various animals; for example certain birds possess spur bones or keratinous spurs used in defense or combat. In humans, a bone spur (osteophyte) is a bony outgrowth that can form near joints and may cause pain or restricted movement.

In transportation and geography, a spur can refer to a secondary railway track that branches from a main line to serve a facility or industry. It can also describe a projecting ridge or line of high ground that extends from a mountain or hill, termed a spur in geomorphology.

In engineering and manufacturing, a spur gear is a gear with straight teeth parallel to the axis, used to transmit motion between parallel shafts. The term also appears in other contexts as a descriptor for various extensions.

As a verb, spur means to urge or stimulate action, often to prompt progress or increase motivation.