If you look at the library online and do a search for "disfellowship", you'll see that it doesn't show up in any of the books that are typically studied with interested ones.
It looks like the word is used mainly in Watchtower articles.
I did find this interesting though. If you filter the results to just the bible it brings up "footnote words indexed". It shows three scriptures...
John 9:22 His parents said these things because they were in fear+
of the Jews, for the Jews had already come to an agreement that, if
anyone confessed him as Christ, he should get expelled from the
synagogue.
John 12:42 All the same, many even of the rulers actually put faith in him,+ but because of the Pharisees they would not confess [him], in order not to be expelled from the synagogue
John 16:2 Men will expel YOU from the synagogue. In fact, the hour is coming when everyone that kills YOU will imagine he has rendered a sacred service* to God.
Anyone else see the irony?