Definitions by Merrian Dictionary

Flat Top 

A ww2 term for Aircraft Carriers

“Scratch one flat top,” radioed during the Battle of the Coral Sea by LCDR Robert E. Dixon to the USS Lexington

Flat Top by Merrian Dictionary September 20, 2022

RN 

Royal Navy

RN Prince Of Wales

RN Hermes

RN by Merrian Dictionary November 20, 2021

ISD 

Imperial Star Destroyer

ISD chimaera

ISD Executrix

ISD by Merrian Dictionary November 24, 2020