Magnitude (astronomy) - Wikipedia
In astronomy, magnitude is a unitless measure of the brightness of an object in a defined passband, often in the visible or infrared spectrum, but sometimes across all wavelengths. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus.. The scale is logarithmic and defined such that each step of one magnitude changes the brightness ...
Magnitude | Definition of Magnitude by Merriam-Webster
the magnitude of the issue can scarcely be overstated the mountain's sheer magnitude usually leaves tourists speechless