a bend of his elbow.
a crease in his trousers.
a flexure of the colon.
a fold in the napkin.
a plication on her blouse.
crease the paper like this to make a crane.
furrow one's brow.
graze the skin.
his face has many lines.
ironing gets rid of most wrinkles.
The dress got wrinkled.
This fabric won't wrinkle.