In mathematics, the word null (from German: null[citation needed] meaning "zero", which is from Latin: nullus meaning "none") is often associated with the concept of zero or the concept of nothing.
A null space of a mapping is the part of the domain that is mapped into the null element of the image (the inverse image of the null element).
For example, in linear algebra, the null space of a linear mapping, also known as kernel, is the set of vectors which map to the null vector under that mapping.
In statistics, a null hypothesis is a proposition that no effect or relationship exists between populations and phenomena.
It is the hypothesis which is presumed true—unless statistical evidence indicates otherwise.