Most of the English words that begin with hex are scientific terms used by mathematicians, chemists, and medical practitioners. A few, however, are encountered in general use.
As a combining form in English, hex- means six.
In geometry, a hexagon is a plane figure having six sides and six angles. The adjective is hexagonal. The adverb is hexagonally.
In geometry, a hexahedron is a solid figure having six faces, especially the “regular hexahedron” or cube. You will encounter the word if you do origami.
The element pod means foot. A hexapod is an animal that has six feet. Insects–which have three pairs of legs–are classed in the subphylum Hexapoda.
In geometry, a hexagram is a figure of six lines. The figure can take more than one form, but the most familiar is that of two intersecting equilateral triangles as seen in the Star of David. Its use as an identifying symbol of Judaism began in the Middle Ages, but its religious usage began much earlier. The symbol, under various names, appears in the imagery of Hinduism, Judaism, Islam, Mormonism, Rastafarianism, Theosophy, and Freemasonry. Known as “Solomon’s Seal,” the symbol is used in magic and witchcraft. In the symbolism of heraldry, the hexagram is called “a mullet of six points.” The Chinese “Book of Changes” (I-Ching) is based on 64 hexagrams that are not interlocked triangles. They are figures of six parallel (whole or divided) lines.
In computing and mathematics, a system of numerical notation that employs 16 rather than 10 as the base is called hexadecimal.
Two hex words outside the mathematical realm are:
A hexarchy is a loose confederation of six states or kingdoms, each governed by its own ruler.
A line of verse made up of six metrical feet is called a hexameter. The hexameter was the standard epic meter in classical Greek and Latin literature.
Finally, there’s the witching word hex, which has nothing to do with six.
The verb hex, “to practice witchcraft,” came into American English from Pennsylvania German settlers.
German hexen, “to hex,” is related to the German word Hexe, “witch.” The English word hag derives from the same source. The earliest English form, haegtesse, was the equivalent of “woman of prophetic and oracular powers.” Does it surprise anyone that the word eventually dwindled into “ugly, bad-tempered, malicious old woman”?
As a noun, a hex is a magical spell or curse.