A facade or charade. Tilings are not as they seem.
Various roles we play in life.
For example, someone who is an authority figure may be seen in a costume depicting a famous leader like Julius Caesar (See Also: Icons).
Mimicry of various real-life scenarios as if in a play. This provides a safe medium for the expression of your perceptions.
Sustenance and support. Among ancient tribal cultures, costumes and masks served as a vehicle for sympathetic magic.
For example, if they needed crops to grow, they might dress as vegetation and perform a jumping dance to encourage that growth. So, what facet of your life does this costume represent, and how does it accent that facet?
[1]1. Disguise, deception.
2. One feels need to assume other roles.
3. One does not feel comfortable presenting one’s own image.
[2]