I caught this weasel word again in Jared Taylor's March 21st interview with ABC news the other day. Taylor's race realism has, the interviewer said, been "discredited."
It hasn't, of course, any more than have Charles Murray's researches. What's going on here, from the psychological point of view, is magical thinking—the power of words, of spells, to make true things untrue, and vice versa. By saying something is "discredited" you make it so.
To discredit the accusation of "discredited," the accusee would have to bring forth a consensus of credentialed experts in the field under discussion—psychometry in Murray's case, biology in Taylor's—denying the position the accusee has taken. This obviously isn't possible in the flow of an interview or debate, so the accusation works rhetorically.
It's still low and cheap, though—a weasel word.