The word "terror-stricken" refers to a state of extreme fear or panic. Its antonyms are words that describe the opposite state of mind, such as "calm," "composed," "serene," or "placid." These words suggest a sense of peace and tranquility, as well as a lack of anxiety or stress. Other antonyms for "terror-stricken" might include "fearless," "courageous," "brave," or "confident," which connote a sense of strength and resilience in the face of danger or adversity. Using antonyms like these can help to convey a sense of contrast between two different states, highlighting the emotions or behaviors that distinguish them from each other.