Select the most appropriate ANTONYM of the given word. Appal

The correct answer is Assure.

1. Understanding the given word:
The word "Appal" (also spelled appall) means to greatly dismay, shock, or horrify someone, filling them with fear, anxiety, or discouragement.

2. Analyzing the options:
• Alarm: Means to make someone feel frightened, disturbed, or anxious. This is a synonym, not an antonym.
• Assure: Means to give confidence, dispel doubts, or comfort someone. This is the opposite of causing dismay or horror, making it the most appropriate antonym.
• Amaze: Means to surprise or astonish someone greatly.
• Astound: Means to shock or greatly surprise someone.

Therefore, Assure is the correct antonym of Appal.