What word means loyalty to one's country?

The word that means loyalty to one's country, on the USCIS reading vocabulary list, is Allegiance. Allegiance is the duty of fidelity owed by a person to the sovereign state of which he or she is a member or subject, and in the United States the concept is built into both the naturalization process and daily civic life.

The Oath of Allegiance, taken at the naturalization ceremony, is the final legal step in becoming a U.S. citizen. The text, set out in 8 CFR section 337.1, requires the applicant to declare on oath that he or she absolutely and entirely renounces all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty, will support and defend the Constitution and laws of the United States against all enemies foreign and domestic, will bear true faith and allegiance to the same, and will bear arms on behalf of the United States, perform noncombatant service in the armed forces, or perform work of national importance under civilian direction when required by law.

The Pledge of Allegiance, recited in schools and at public events, also uses the word: "I pledge allegiance to the flag of the United States of America, and to the republic for which it stands, one nation under God, indivisible, with liberty and justice for all." The Pledge was written in 1892 and adopted by Congress as the official pledge in 1942 (codified at 4 U.S.C. section 4); the phrase "under God" was added in 1954.

Allegiance does not necessarily prohibit dual nationality: U.S. law permits dual citizenship, and Supreme Court cases such as Afroyim v. Rusk (1967) and Vance v. Terrazas (1980) limit the government's ability to strip citizenship absent intent to relinquish it.