Bindu

(“drop”) In the Shrividya school, a particular branch of the esoteric ritual tradition known as tantra, the bindu is the
name for the dot in the very center of the
shrichakra, which is a Shrividya symbolic diagram (yantra) used in worship.
The shrichakra is composed of nine
interlocking triangles—four pointing up
and five pointing down—surrounded by
a double series of lotus petals and exterior circular and angular walls. The
bindu symbolizes the ultimate unity of
the divine principles, Shiva and Shakti,
and by extension the unity of all reality.
For further information see Douglas
Renfrew Brooks, The Secret of the Three
Cities, 1990.