From LOA 91, "Consolidated Small Jet Agreement":


Definitions of Small Jets

A “Small Jet” will be defined as a jet aircraft that is a Small SJ, Medium SJ, or Large SJ, as defined below.

“Small SJs” are defined as jet aircraft with a certificated maximum seating capacity of 44 seats and a certificated maximum gross takeoff weight of 46,600 pounds. Any CRJ-240/400 aircraft configured for more than 40 seats shall be defined as a Medium SJ.

“Medium SJs” are defined as jet aircraft with a certificated seating capacity of no less than 45 seats and no more than 50 seats and a certificated maximum gross takeoff weight not greater than 65,000 pounds

“Large SJs” are defined as jet aircraft having a certificated seating capacity of 51-70 seats and a certificated maximum gross takeoff weight not greater than 75,000 pounds. In addition Large SJs include (a) the EMB-170 aircraft with a maximum certificated seating capacity of 78 seats and a certificated maximum gross takeoff weight of 82,100 pounds and (b) the EMB-175 aircraft with a maximum certificated seating capacity of 86 seats and a certificated maximum gross takeoff weight not greater than 86,000 pounds.

From LOA 96, "Transition Agreement":

B. Section 1.D.2 of the America West collective bargaining agreement will be modified to increase the maximum seating capacity of jet aircraft flown by Express carriers to a maximum seating capacity of 88 seats (or up to 90 seats if there are no first class seats) and/or certificated maximum take off weight of up to 90,000 pounds.

C. The US Airways and America West collective bargaining agreements will be modified to allow for a combined maximum of ninety-three (93) CRJ-900, or other aircraft within the seating and maximum take-off weight limits specified in Paragraph B above, to be operated in revenue service at any given time at Express Carriers.

I think you ARE making that up. Please provide a reference for the usage of the "Larger than Large Small Jet" terminology in a US Airways or America West CBA/LOA document.