The swordfish has a stout, fairly rounded body and large eyes. The second dorsal fin is quite separate from the first and very small. The anal fins approximate the shape of the dorsal fins, but are noticeably smaller. Ventral fins, found on the underside of fish, are absent.
Adult swordfish have neither teeth nor scales.
The swordfish snout elongates into a true sword shape. Measuring at least one-third the length of the body, it is long, flat, pointed, and very sharp. The lower jaw is much smaller, though just as pointed, ending in a very wide mouth. Swordfish coloration varies greatly among individuals. The dorsal side can range from dark brown to grayish-blue.