The exhortation of 1 Cor 5:11 is translated from the Greek word "synanamignyasthai" (literally "to be mixing selves up with") and is translated by the Dubs in the NWT as "quit mixing in company with". The WTS teaches that this is equivalent to their "disfellowshiping" procedure.
However, the same word "synanamignyasthai" is used by Paul at 2 Thessalonians 3:14 in a discussion of how to treat christians who rejected the apostle's teachings. Yet the NWT renders it as "marked, stop associating with" and is used by the WTS as a key text in its "marking" procedure. "Marking" is a procedure that the WTS has whereby those congregation members who are doing things that are not quite right, but not warranting judicial action, are to be "marked" i.e. not afforded all the privileges of normal social fellowship, but they still are able to do all the things with the congregation that others do, but not socialise. Interestingly, this is an individual matter, not a congregation matter i.e. each congregation member decides for himself or herself whether to "mark" another or not.
So we have the situation where the same word "synanamignyasthai", used by the same Bible writer, is rendered in two different ways by the WTS and worse, is used to substantiate their own peculiar shunning practices, namely "disfellowshiping" and "marking".
Also of interest is that it's used by Paul in 2 Thessalonians to refer to ones who were "not obedient to our word", which in modern-day WTS parlance is apostasy!!!!! Yet they are simply to be "marked", not "disassociated" or "disfellowshiped".