In the SCA an Unbelted Fighter is one who has received the accolade of admission into the order of the Chivalry. That is to say, a non-Knight/Master of Arms.
Collectively referred to as the "unbelts" especially in the context of Pennsic champions teams. As in, "The East won the Unbelts this year."
Contrast with with the use of belted to refer to Knights. As in, "The Middle won the Belted Champs this year.