Allusion and illusion

These words are often confused. An allusion is a reference or mention.

• This book on Indian history makes a brief allusion to the Mesopotamian Civilization.
• The teacher made an allusion to Indian mythology.

An illusion is a false impression. It is something that seems to exist but doesn’t.

• Mirrors give an illusion of more space in a room.
• The illusions of youth fade with maturity.
• The sky blue ceiling gave me the illusion that I was outdoors.