Inversion means reversing or flipping the normal order or position of things. When you read a sentence that says “Never have I seen such a sight,” instead of the usual “I have never seen such a sight,” that's inversion: the verb comes before the subject. Writers and speakers use inversion to add drama or emphasis to their words.

In science, inversion describes situations where the usual arrangement gets turned upside down. A temperature inversion happens when warm air sits on top of cold air instead of the normal pattern, where warm air rises. This trapped cold air can hold pollution close to the ground, making smog worse in cities.

In music, when you play the notes of a chord in a different order, you're creating an inversion of that chord. If a C major chord normally has C on the bottom, playing it with E or G on the bottom creates an inversion.

Whether you're inverting a fraction in math (flipping 3/4 to become 4/3), inverting an image, or inverting the usual way of doing something, you're taking what's normal and turning it around.