Which prefix signifies "large"?

The prefix "macro-" signifies "large" or "long." This prefix derives from the Greek word "makros," meaning large or long. In various contexts, "macro-" is used to describe something that is extensive in size, scale, or scope. For example, in terms like "macroeconomics," it refers to the broad aspects of economies rather than individual markets, indicating a large-scale perspective.

In contrast, "micro-" refers to something small, often used in science and technology to denote tiny objects or concepts, such as "microorganism." The prefixes "astro-" and "photo-" relate to celestial bodies and light, respectively, and do not indicate size in a direct manner related to the meaning of "large." Thus, "macro-" is the appropriate choice to denote largeness.