Definition 1:
Two person
game played with
Go stones on a field of
hexagons, on variously shaped boards, invented by
Piet Hein, in the late 40's, and independantly, a few years later by
John Nash (his original board is preserved in the faculty lounge at
Princeton). Often, in the US, played in old bathrooms with
honeycomb tile -- hence the name "
John", for its inventor, who was known for playing other kinds of games in the john, as well. (Me bad! Me very bad!!)
Dr. Nash has proven in 1949 that there is an unbeatable first-person strategy for any given game of Hex, but it's not known what that is.
Definition 2:
In American folk magick, a hex sign is a round plaque characteristic of the Pennsylvania Dutch, with designs based on the 6-leaved rose (in the mathematical sense) which are often combined with other emblems such as the distlefink (thistle finch), clover and oak leaves, tulips hearts, etc., used as a charm against lightning and to promote fertility.