Magnitude refers to the size or quantity of something. In science, it is often used to describe the intensity of a physical phenomenon such as earthquakes or the brightness of a star. [Intensity means the strength or force of something.]
For instance, in science, it is used to describe the intensity of events like earthquakes, which measures the strength or force of the shaking. Magnitude can also be used to describe the brightness of stars, indicating their level of luminosity [how much light they give out].
Very Simple Definition:
Magnitude means how big or strong something is. In science, it is used to describe how bright or powerful things like stars or earthquakes are. For example, it can measure how bright a star is, or the strength of an earthquake.