circul

Circul is a linguistic combining form derived from the Latin circulus, meaning a small circle. It is used in English and other languages to form terms that convey ideas of circle, roundness, or movement along a circular path. The form appears in a range of words whose core sense involves circularity, such as circular, circulate, circulation, circulatory, circulant, and circuitry. It is typically affixed to stems to produce adjectives, nouns, or specialized technical terms.

In usage, circul- terms span many fields. In biology and medicine, circul- appears in words describing movement of substances through the body, most notably the circulatory system and circulation of blood. In mathematics and computer science, circulant (or circulant matrices) denotes structures with rotational symmetry, while circular buffers and circular queues in programming use wrap-around indexing that reflects the same circular idea.

The form is generally not used as a stand-alone word in modern English; instead, it functions as a productive morpheme attached to roots to form related concepts. Cross-linguistically, cognates appear in languages that borrowed Latin roots, often with spelling adjustments (for example, forms corresponding to circle, circular, or circulate). The circul root thus serves as a compact way to package the concept of a circle or cyclical movement across disciplines. See also circular, circulation, circulatory, and circulant.