A more thorough explanation:

Definition: Equinox (ee-kwuh-noks or ek-wuh-noks) is a time of the year when day and night are of equal length. There are two equinoxes in a year, one in March and the other in September.

Example: During the equinox, the sun is directly above the equator, and the length of day and night is almost equal all over the world.

Explanation: The example illustrates the definition of equinox by explaining that during this time, the day and night are almost equal in length all over the world. This happens because the sun is directly above the equator, and the earth's axis is not tilted towards or away from the sun.