Dacorum may mean any of the following:

• Dacorum is a Latin word meaning "of the Dacians", the inhabitants of Dacia, as in "Cohors Primae Dacorum", the cohorts recruited from Roman province of Dacia.
• Dacorum is a (medieval) Latin word meaning "of the Dacians", a medieval Latin term for the inhabitants of Denmark, now know in English as Danes.
• Dacorum is a local government district and borough in Hertfordshire, England. That borough name derives from the medieval Latin Dacorum designating the Danes: see Dudo of St. Quentin's Gesta Normannorum or the story of Rollo of Normandy.