Rógin represents the actual word used by the Rohirrim that is usually translated into archaic English as 'woses'. That word in turn derives from Old English wása via Middle English wous, and though its original derivation is open to question, in context the term clearly means 'wild man'. While we cannot be absolutely sure that Tolkien meant rógin and 'woses' to share their literal meaning, this does seem to be a fair assumption.