Notformer:
You got me thinking. Did the WT coin the term themselves?
No. The term 'disfellowship' was first used as a verb in the 1830s. The term is used by various minor Protestant groups (which is what JWs are at their core), though the specific application of the term varies. For example, Christadelphians also practice what they call 'disfellowshipping', but it generally involves exclusion from their church services but not strictly mandated social shunning.