Definitions
1.nounAny sheet of paper or cardboard, folded into three sections along two parallel creases and used to present information, typically as a brochure or display board.
2.nounA wallet with three equal-sized sections that fold together.
3.nounAnything folded into thirds to resemble a trifold.
4.adjectiveThreefold
5.adjectiveOf a mirror: having three reflective surfaces hinged together.