Deportment: behavior; demeanor; conduct; how someone behaves in company.
The word deportment took a familiar road on its way into the English language. It started out as a few Latin words.
The preposition de, in Latin, means: away. The verb portare, means: to carry. Together, they form the Latin verb deportare, which primarily means: to bring. This verb, however, has a secondary meaning: to convey. Here we discover the root of the modern English word. How one conveys, or carries oneself in public is deportment.
Of course, before the word showed up in English, it travelled the well-worn road through French as déportement, which means, basically, the same thing.
At one time, it was proper in English to “deport” oneself. The word carried the same meaning as deportment. Both words referred to behavior. Over time, however, this meaning slipped away and deportment won.
These days, to deport is to kick someone out of the country. Perhaps we should only deport those with poor deportment.