As Webster 1913
says, a perversion
is most generally and accurately defined as a diversion
from the true (or original) intent or object of a thing. Can be minor
, depending on how radical
the diversion is.
When used as shorthand for "sexual perversion", this becomes relative to what one believes the true or original intent of sex is. Radical Catholics may believe it to include anything other than the missionary position, while radical liberals may argue that it only encompasses that which is not consentual.