IPA: /kəmˈpɔːtmənt/
KK: /kəmˈpɔrtmənt/
The way a person behaves or conducts themselves, especially in a formal or social situation.
Her comportment at the dinner party impressed all the guests.
Comportment is formed from "com-" (meaning together) and "portare" (meaning to carry). The word refers to the manner in which one carries oneself or behaves, thus indicating one's behavior or demeanor.
Think of how you 'carry' yourself ('portare') in a way that is 'together' ('com-') with social norms — that's what comportment means.