undulating

Undulating is an adjective describing something that has a wave-like form or movement. When applied to surfaces, landscapes, or boundaries, it indicates a smooth succession of rising and falling contours rather than straight lines or flat planes. In motion, undulating describes a rhythmic, wave-like movement that travels through a body or object, often without abrupt transitions.

Etymology: The term derives from late Latin undulatus, from unda “wave,” with the sense of forming or moving in waves.

In geography and geology, undulating terrain refers to land with gentle hills and dips, contrasting with flat plains or sharply folded mountains. An undulating coastline describes shores where the shoreline curves in alternating bays and promontories. The term can also describe surfaces of materials that exhibit waviness, such as undulating metal sheets or textiles with a wave-like pattern.

In biology and physics, undulations are common in locomotion and wave phenomena. Snakes and eels move by lateral undulations of the body; many fish employ body waves to propel themselves, a form of anguilliform propulsion. In physics, undulation denotes the crests and troughs of a wave, or the oscillatory motion of a system such as light, sound, or water waves.

Usage: The word is used across science, engineering, geography, and design to emphasize motion or form that is smooth and periodic rather than abrupt or angular, offering a concise description of waviness in both structure and movement.