Armor vs. Armour
“Armor” is the standard US spelling; “armour” is the standard UK spelling of the same word. Do not treat one form as universally wrong: the choice is regional orthography, including in compounds such as body armor/body armour.
“Armor” is the standard US spelling; “armour” is the standard UK spelling of the same word.
Key details
Further guidance
Core difference
“Armor” is the standard US spelling; “armour” is the standard UK spelling of the same word.
Fast Test
Choose the spelling required by the document’s regional or house style and keep it consistent.
Usage Boundary
Do not treat one form as universally wrong: the choice is regional orthography, including in compounds such as body armor/body armour.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Armor — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct dictionary evidence identifying armor as the US spelling of armour.
- Armour — Cambridge Dictionary (opens in a new tab)Cambridge University Press · Direct dictionary evidence identifying armour as the UK spelling corresponding to US armor.