Patriotism means loyalty of a person to his/her own nation or the leaders of the nation. A patriot is a person who is on the side of his/her own nation or its leaders. Patriotism is different from nationalism. Also, contrary to a nationalist, patriots do not favor imperialism, while nationalists tend to but don’t always favor imperialism. An example of a nationalist favoring imperialism would be Adolf Hitler.
The English term "patriot" is first known from the Elizabethan era, via Middle French from Late Latin (6th century) patriota "countryman", ultimately from Greek πατριώτης (patriōtēs) "countryman", from πατρίς (patris), "fatherland". The abstract noun patriotism appears in the early 18th century.