The following comprises a list of words and phrases of the Armed Forces of the United Kingdom of Great Britain during the Great War, which also includes slang of the trenches and the Air Force; British and American service terms and expressions in everyday use; nicknames, sobriquets, and the titles of British and Commonwealth Regiments and their origins; and warfare in general. These words and phrases are contemporary to the war, which is reflected in the style and language used of the time, some of which may seem derogatory by today's standards. The following words and phrases have been transcribed from three primary sources (see contents). Feel free to help improve any of the entries in these lists.
- Hague Tribunal
- Hair-brush grenade
- Hairy
- Half-Crown Battalion
- Half inch
- Halfpenny, Five pence
- Ham diet
- Hammer blows
- Hammer, Swing the
- Hammer, That's the
- Hand cart cavalry
- Handy Billy
- Hans wurst
- Hard-lying money
- Harkers
- Harry Freeman's, It's
- Harry Tate's Cavalry
- Harry Tate's Navy
- haymaking drill
- Hazy Brook
- Head worker
- Heavy stuff
- He kaina no katoa
- Hectic show
- Hedge hopping
- Heine
- Hell Fire Corner
- Herbaceous borders
- Heroine of Loos
- Hickaboo
- High jump, On the
- High stepper
- High-tailing
- Hipe
- Hitchy-koo
- Hitting the roof
- Hob, On the
- Hobo
- Home Service Battalions
- Honourable Artillery Company
- Honours of War
- Hostages
- Howitzer
- Hun
- Hydro-aeroplane
- Hydroplane
- Hypo helmet