Stoic /ˈstō-ik / noun, adj. 

Definition: As a noun, stoic refers to a person who can walk through pain and hard times without complaining or showing their pain. It can also refer to someone who belonged to the ancient philosophical school of Stoicism. 

Etymology:  Originally the word stoic referred to the 4th century Greek philosophical school that taught that fortitude, justice and self-control were the antidote to passion, which was seen as the cause of evil.

By the 14th century the term had been adopted in English as a term used to generally describe a person who could face adversity without being overly emotional. By the 15th century it was used as an adjective for one who is not affected by either feelings or passions.

In a Sentence

The Stoic school at Athens taught students that showing emotional displays was the cause of all evil.

While Native Americans are often seen as stoic in the movies, in real life they can be quite funny.

Angela’s face was so stoic at the children’s party, especially because she has always been afraid of clowns

Synonyms 

Tolerant, Passive

Antonyms 

Passionate, Demonstrative