What prefix indicates that something is around or surrounding?

The prefix that indicates something is around or surrounding is "peri-." This prefix originates from the Greek word "peri," which translates to "around" or "about." It is commonly used in various medical and scientific terms. For instance, in anatomy, "pericardium" refers to the membrane surrounding the heart, and "peripheral" relates to the outer boundaries or surrounding areas of a structure or system.

In contrast, the other prefixes have different meanings: "per-" often implies through or completely, "para-" can mean alongside or abnormal, and "circum-" means around as well, though it is not as commonly used in medical terminology as "peri-." Thus, "peri-" is the most accurate choice in this context when referring to something that is around or surrounding.