Which word describes something that is opposite or not direct?

The term "inverse" refers to a relationship or a value that is opposite to another. In mathematics and science, it often denotes a quantity that negates or reverses the effect of another; for example, the inverse of addition is subtraction, and the inverse of a function can refer to its reciprocal. This captures the concept of something being opposite or not direct.

In contrast, "linear" relates to relationships that follow a straight line or a direct proportionality, while "subset" pertains to a set that is part of a larger set, which does not imply opposition. Lastly, "correlate" describes a relationship where two variables move together but does not indicate that one is opposite to the other, nor does it convey the notion of being not direct in the same way as "inverse." Thus, "inverse" is the most appropriate choice for describing something that is opposite or not direct.