The Yod aspect pattern includes 3 planets arranged in a long triangle, with one planet (apex) in Quincunx aspect to the other two, and the other two in Sextile aspect to each other. (See diagram at right.)
The Yod is a source of irritation and frustration, but can also raise awareness, particular through the energy of the apex planet. We need to utilize the Sextile more, in order to "steer" the apex planet.
If the apex planet forms an Opposition to a fourth planet, this is often called a Yod Kite (also sometimes called a Boomerang).
In the Huber school of astrology, which uses aspect configurations extensively, the Yod is called a Projection Triangle and the Yod Kite is called a Striving Figure. See Bruno and Louise Huber's book Aspect Pattern Astrology for excellent information about aspect patterns.
Pronounced: YAWD (rhymes with odd). Sometimes pronounced YODE (rhyming with road).