So, conspiracy theory has been around for ~150 years in the English language: Etymonline.com
Conspiracy theory "explanation of an event or situation involving
unwarranted belief that it is caused by a conspiracy among powerful
forces" emerged in mid-20c. (by 1937) and figures in the writings of,
or about, Charles Beard, Hofstadter, Veblen, etc., but the degree of
paranoia and unreasonableness implied in each use is not always easy
to discern. The phrase was used from 19c. in a non-pejorative sense
"the theory that a (certain) conspiracy exists," especially in court
cases. Its use in general reference to theories of hidden cabals
pulling wires behind the scenes of national or global events is by
The OED definition is: OED
the theory that an event or phenomenon occurs as a result of a
conspiracy between interested parties; spec. a belief that some covert
but influential agency (typically political in motivation and
oppressive in intent) is responsible for an unexplained event.
has there been a subtle shift in the definition of the phrase
"conspiracy theory" in recent years?
My sense is there has been no change in the definition, but usage has increased and the actors have changed: from state actors to individuals who feel affronted by " the man!"