Gegenzahl
... German for opposite number, additive inverse (externer Link)
The Opposite number, also called the additive inverse, is the negative version of any number. For example, the opposite of 4 is -4. It also works the other way round: the opposite of -8 is 8. On a number lines, two numbers that are opposite to each other lie on opposite sides of the number 0 and both have the same distance to 0.