Comitatus can be:

• an old Latin word meaning company or retinue or an armed group of men attached to a leader
• in the Classical Times and in the Middle Ages, a political term used in various meanings: see Comitatus (Classical meaning)
• in the Middle Ages, the Latin word for county in the sense of a territory under a count ("comes"): see county and count
• nowadays, in legal texts sometimes an alternative word for county as it is used in the USA: see county
• an administrative unit of the Kingdom of Hungary, often but inaccurately also called county: see Comitatus (Kingdom of Hungary)
• an administrative unit in present-day Hungary, often also called county: see Counties of Hungary