Coincident is a geometric term that pertains to the relationship between two vectors. Vectors consist of a "magnitude" and a "direction". Vectors can be said to be coincident when their direction is the same though the magnitude may be different; that is to say, they lie one on top of the other. If two coincident vectors were to be normalized, the resulting vectors would be identical. The dot product of two coincident vectors is the product of their magnitudes. The cross product of two coincident vectors is a vector of all zeros.
