1. a line or mark made by folding, pressing, or wrinkling something
2. a sharp fold in clothing, especially trousers

1. to make a crease or creases in something by folding or pressing
2. to become wrinkled or folded

Examples

• There was a deep crease in the paper where it had been folded.
• His pants had a sharp crease down the front.
• She tried to smooth out the creases in her shirt.
• Be careful not to crease the important documents.
• The fabric will crease if you pack it too tightly.
• He ironed his shirt to remove all the creases.
• The map had permanent creases from years of folding.