An evil spell or curse.
A witch.
A spell (now rare but still found in compounds such as hex sign and hexcraft).
To cast a spell on (specifically an evil spell), to bewitch.
A number system with base sixteen, using the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F, most used in computing as a hexadecimal digit can represent four bits, half a standard byte.
A number expressed in the hexadecimal system.
A hexagonal space on a game board.
A hexagon-shaped item of rock climbing equipment intended to be wedged into a crack or other opening in the rock.