Calibres refer to measurements or diameters of firearms, but there are several synonyms for this word that could be used in a variety of contexts. One such synonym is "gauge," which is often used to refer to the diameter of shotguns. Another option is "size," which is a broad term that could apply to anything from clothing to machinery. "Dimensions" is also a synonym, which can refer to the length, width, and height of an object. "Magnitude," "range," and "capacity" are additional synonyms that can be used to describe the size, capability, or potential of something.