The following game-specific abbreviations are commonly found in the game and on the official forums. This list isn't intended to be a catch-all for every imaginable abbreviation, only those that are important and used relatively frequently.
- AA - Anti-Air.
- AAR - After Action Report.
- AC - Armoured Car brigade.
- ARM - Armoured brigade. Medium tanks.
- ARMA - The HoI2 expansion pack: Armageddon.
- Art or Arty - Artillery brigade.
- ASW - Anti-Submarine Warfare.
- AT - Anti-Tank.
- BB - Battleship
- BC - Battlecruiser
- BP - Bitter Peace (the event when Germany controls certain Russian cities)
- Bgd or bde—Brigade
- CA - Heavy Cruiser
- CAG - Carrier Air Group
- CAS - Close Air Support
- CAV - Cavalry or Semi-Motorized Cavalry
- CG - Consumer goods
- CGM - Custom Game Mode
- CL - Light Cruiser
- CTD - Crash to desktop (usually because of a bug)
- CV - Carrier
- CVL - Light Carrier
- CVN - Nuclear-Powered Carrier
- CTF - Carrier Task Force
- DD - Destroyer or the HoI2 Expansion pack: Doomsday
- DoW - Declaration of War
- Div - Division
- EF - Expeditionary Force
- Eng - Engineer Brigade
- ESE - Effective Supply Efficiency (HoI 2 only)
- EscF - Escort Fighter (not in HoI3 vanilla)
- ETA - Estimated Time of Arrival
- Exp or XP - Experience
- FM - Field Marshal
- Ftr - Fighter
- Gar - Garrison
- GC - Grand Campaign (1936 Scenario)
- GDE - Ground Defence Efficiency
- Gen. - General, a leader rank
- GIE - Government in Exile
- GoI - Guarantee of Independence
- H Arm - Heavy Armour
- HA - Hard Attack value
- HoI - Hearts of Iron, version 1
- HoI2 - Hearts of Iron, version 2
- HoI2DD - Hearts of Iron, version 2 with Doomsday expansion
- HoI2DD ARMA - Hearts of Iron, version 2 with Armageddon expansion. Also known as just ARMA.
- HoI3—Hearts of Iron 3
- HQ - Headquarters
- IC - Industrial Capacity
- Inf - Infantry brigade
- INT - Interceptor
- L Arm - Light Armoured brigade
- Lt.G. / Lt.Gen. - Lieutenant General, a leader rank
- MAR - Marines
- MBT - Main Battle Tank
- Major - Usually major Power, Germany, UK, USSR, US, Japan
- MEC - Mechanized Infantry
- MIL - Militia
- Minor - minor Power, any nation that is not a major or regional Power
- Mj.G. / Mj.Gen. - Major General, a leader rank
- MOT - Motorized Infantry
- MP - Multiplayer or Manpower or Police brigade
- MRP / M-R-P - Molotov-Ribbentrop-Pact, also known as Hitler-Stalin-Pact
- MTN - Mountain Infantry
- NAV - Naval Bomber
- NU - National Unity
- OOB - Order of battle. The inventory of units that a nation has.
- OOS - Out of supply.
- Org - Organisation level of division
- PAR or Para - Airborne Infantry (Paratroopers)
- R Art - Rocket artillery brigade
- SA - Soft Attack value
- SAG - Surface Action Group (a fleet that doesn't include carriers)
- SCW - Spanish Civil War
- SH Arm - Super Heavy Tank brigade
- SP - Single Player or Self-Propelled, usually as a prefix to another abbreviation, such as SP-A (Self-Propelled Artillery)
- SS - Submarine
- Str - Strength of a unit.
- STR - Strategic Bomber
- TAC - Tactical Bomber
- TC - Transport Capacity (HoI 2 only)
- TD - Tank Destroyer brigade
- TP - Transport Ship
- TRA - Transport Plane
- VP - Victory Point
- WAD - Working as Designed
- WC - World Conquest