Analyzing Word Choice in Emotional Context

Read the following excerpt from a short story:

"As the clock ticked steadily, she felt a growing sense of trepidation creeping in. The dim light of the room cast long shadows, and the silence was punctuated only by the occasional rustle of leaves outside. Her heart raced as she prepared to face the unknown, each moment stretching into eternity."

In this excerpt, the word trepidation is used to convey a specific feeling. What does this word choice suggest about the character's emotions?