The prefix "intra-" means "inside" or "within". It is commonly used in English to describe something that is happening within a single group or place. For example, "intravenous" means "within a vein". Other examples of words that use the prefix "intra-" include "intranet" (a computer network with access that is restricted to a specific group of people) and "intracellular" (existing, occurring, or functioning within a cell) .