"turned in the opposite direction, having an opposite course or tendency," in early use also enverse, mid-15c., from Latin inversus, past participle of invertere "turn about, turn upside-down, upset, reverse, invert" (see invert). Related: Inversely. As a noun, "inverted state or condition," 1680s, from the adjective.
a term is in inverse proportion to another term if it increases (or decreases) as the other decreases (or increases)
when the direct approach failed he tried the inverse
inventive
inventor
inventory
inveracity
Inverness
inverse
inversion
invert
invertebrate
invest
investigable