- HET
- Acronym:Hazardous Enviroment Training
- HMG
- Acronym:Heavy Machine Gun
- HQ
- Acronym:Headquarters
- HUD
- Abbreviation:Head Up Display
- I RB
- Definition:Military Service Registration Board: Files dealing with claims for disability arising out of Pre-Truce service. These files deal with proof of service ,(wound and death under the Act 1932); from 1932 to 1957.
- ICRC
- Abbreviation:International Committee of the Red Cross
- IDP's
- Definition:Internally Displaced Persons
Internally Displaced Persons
- IED
- Acronym:Improvised Explosive Devise
- IFOR
- Abbreviation:Implementation Force
Implementation Force - was a NATO-led multinational force in Bosnia and Herzegovina under a one year mandate from 20 December 1995 to 20 December 1996 under the codename Operation Joint Endeavour
- IFR
- Abbreviation:Instrument Flight Rules
- II RB
- Definition:Military Service Registration Board: Files dealing with claims for disability arising out of Pre-Truce service. These files deal with proof of service ,(wound and death under the Act 1932); from 1932 to 1957.
- III MSRB
- Definition:Military Service Registration Board: Files dealing with claims for disability arising out of Pre-Truce service. These files deal with proof of service ,(wound and death under the Act 1932); from 1932 to 1957.
- IMOSOC
- Acronym:International Military Observer and Staff Officers Course
- IRAM
- Abbreviation:Irish Refugee Agency Macedonia
- IRB/A
- Definition: Military Service Registration Board: dealing with proof of service (wound).
- IRSG
- Abbreviation:Irish Rwandan Support Group
- ISAF
- Acronym:International Security Assistance Force (Afghanistan)
- ISR
- Acronym:Intelligence Surveillance and Reconnaissance
- ISTAR
- Acronym:Intelligence Surveillance Target Acquisition and Reconnaissance
- KFOR
- Abbreviation:Kosovo Force