Answer
The temperature 0 K is called absolute zero because it is the lowest possible temperature in the universe. The temperature 0 K is fundamentally different from $0^{\circ}C$ and $0^{\circ}F$ because 0 K is a lower limit on temperatures in the universe.
Work Step by Step
The temperature 0 K is called absolute zero because it is the lowest possible temperature in the universe. The temperatures $0^{\circ}C$ and $0^{\circ}F$ are zero points on temperature scales which are useful in everyday life, however it is possible for temperatures to drop below $0^{\circ}C$ and $0^{\circ}F$. However, the temperature 0 K is fundamentally different because it is a lower limit on temperatures in the universe.
