Arcus

Arcus is a term derived from the Latin arcus, meaning bow or arch. In scientific and clinical usage, arcus denotes a curved or ring-shaped structure, or a feature that resembles an arch. The exact meaning depends on the field, but the common idea is a curved form.

In anatomy and medicine, arcus aortae (the aortic arch) is the curved portion of the aorta that gives off branches to the head, neck, and upper limbs. Another widely used term is arcus corneae, or arcus senilis, a circular opacity at the margin of the cornea caused by lipid deposits; while common with aging, it can signal lipid disorders when appearing in younger people.

In skeletal anatomy, arcus zygomaticus, the zygomatic arch, forms the cheek prominence and connects the zygomatic bone to the temporal bone.

In meteorology, arcus (arcus cloud) refers to a low, horizontal, curved cloud band that forms along the leading edge of a thunderstorm's gust front and can indicate gusty winds and severe weather.

The term arcus appears in other anatomical terms for arch-like structures, and in general usage it remains a descriptor for curved shapes across disciplines.