circum

Circum is a Latin prefix meaning around, surrounding, or on all sides. In English, circum- attaches to base words to indicate distance, position, or relation to a boundary, and it forms a wide range of terms across science, mathematics, medicine, and everyday language. The prefix comes from Latin circum-, and it entered English through Latin and Old French during the medieval period.

In mathematics and geometry, circum- terms describe the outer boundary or enclosing circle of figures. Circumference is the distance around a circle. A circumcircle is the circle that passes through all vertices of a polygon, and a circumcenter is the center of that circle. The circumradius is the radius of the circumcircle. To circumscribe means to draw or construct a figure around another figure, enclosing it with a boundary.

In medicine and general usage, circum- appears in words such as circumcision, the surgical removal of foreskin around the glans. In descriptive language, circumstantial and circumstantial evidence refer to surrounding conditions and circumstances rather than direct evidence. The verb circumvent uses circum- in the sense of going around an obstacle or difficulty.

See also related terms such as circumscribed, circumference, circumnavigate, and circumpolar. Circum- is a productive prefix in English, forming many compounds that convey ideas of surrounding, enclosing, or encircling a thing or area. It should be distinguished from circa, which means approximately or about in dating and estimation.