Sumbu

Sumbu is a term in Indonesian and Malay meaning axis, shaft, or spindle. It refers to a central line or rod around which something rotates or is aligned, and is used across science, engineering, and everyday language to denote an axial element.

In engineering, sumbu designates shafts and axles that transmit motion or support rotating parts. Common compounds include sumbu engkol (crankshaft) and sumbu roda (wheel axle). The term often appears with poros as a synonym for shaft in technical writing.

In mathematics and physics, sumbu is used to describe coordinate axes such as sumbu x, sumbu y, and sumbu z, which define directions in a plane or space. It also denotes the axis of rotation of a body, for example the sumbu bumi (Earth's axis).

In astronomy and related sciences, the word is used in phrases describing the rotational axis of planets and stars. In everyday language, sumbu can also mean a central line or axis around which a system or argument is organized.

Etymology: The word is native to Indonesian and Malay, widely used in Southeast Asia. It forms part of many compound terms in technical literature and education, and is often distinguished from, yet related to, the term poros which also means shaft or axle.