Americans gathered together and had a increased sense of patriotism

in the sentence, what does the suffix in the word patriotism mean?
a belief or principle
a fear of something
a specific person
a strong foundation

The suffix "ism" in the word patriotism means a belief or principle.

In the word patriotism, the suffix "-ism" indicates a belief or principle. It turns the root word "patriot" into a noun and refers to the love and devotion towards one's own country.