Tax treaty definitions clarify persons, enterprises, taxes and competent authorities to determine tax jurisdiction and treaty application. Article 3 defines core terms for the India-Armenia tax convention: territorial scope for 'India' and 'Armenia'; 'person', 'company', 'enterprise', 'enterprise of a Contracting State' and 'international traffic'; the competent authority for each State; 'national' as individuals and juridical persons under domestic law; 'tax' limited to Indian or Armenia taxes excluding penalties; 'fiscal year' for India and Armenia; and a rule that undefined terms adopt their contemporary meanings under the domestic tax law of the applying Contracting State.