This is a
Japanese term from the game of
Go (
Wei Qi/
Badouk). It refers to a certain type of move, usually described in
English as the "
knight's move," due the fact that the two stones form the same shape as the move made by a
knight in the game of
chess. In fact, the
Japanese word "keima" comes from the name of the equivalent piece in the Japanese game of
Shogi. A move is called "keima" if the stone placed is on a vertex two spaces in one direction and one space in an
orthogonaldirection from a previously placed stone of the same colour, with no stones in the intervening spaces. If there was a friendly stone in one of the intervening spaces, the move would be a
nobi (
stretch) from one and a
kosumi (
diagonal connection) from the other. I have no idea what it would be called if there was a stone of the opponent's in the breach (a strange hybrid of a
pincer and a
clamp, perhaps), but it wouldn't be something you'd play very often anyway. In the diagram below, playing at any of the places marked "*" would be considered a
keima from the stone marked "o," in the absence of intervening stones.
.......
..*.*..
.*...*.
...o...
.*...*.
..*.*..
.......
A keima is a rather balanced move, more aggressive than an ikken tobi (one-space jump) and certainly more so than a nobi (stretch) or kosumi (diagonal connection), but much stronger and harder to cut than either ogeima (large knight's move) or niken tobi (two-space jump), at the expense of being slower. It is considered to be better for attacking than defense, since it can be cut if the attacker is strong in the vicinity, but is used in more ambiguous situations, where attacking with a stronger move like ogeima or niken tobi would be overplay, due to being too thin, or simply if the keima attacks at a weaker point than would either ogeima or niken tobi.
The keima is often seen in what is probably the most common shimari (corner enclosure), often referred to as a keima shimari (for obvious reasons) and consisting of stones at the 4-3 and 3-5 points, as shown below (edges of the board marked with ###):
#......
#......
#..o,..
#....o.
#......
#......
#######
("," is the corner hoshi (star point) and is only for reference. It has no game effect, and can be ignored if you don't know what it is.)
The two stones form a keima with one another, as can be easily seen. For a more detailed discussion of shimari, see the shimari node, and for an analysis of this particular shimari, see keima shimari.