What term describes someone who is imperturbable?

The term "imperturbable" refers to a state of being calm and unable to be upset or excited. Therefore, someone who is imperturbable maintains a steady demeanor regardless of external circumstances, demonstrating composure and restraint. This matches with the characterization of being calm and collected, as such individuals are typically not easily ruffled by stress, chaos, or emotion.

In contrast, terms associated with the other choices carry meanings that directly conflict with the idea of being imperturbable. For instance, being rash and impulsive suggests a tendency to act quickly without thought, which is contrary to the steady, composed nature of an imperturbable person. Indecisive and confused implies a lack of clarity and certainty, resulting in a frazzled state of mind rather than the calmness that defines being imperturbable. Additionally, emotional and reactionary describes someone who responds strongly to stimuli, exhibiting behavior that is the opposite of the calmness and steadiness implied by imperturbability.