n.
Function: noun
Date: 13th century
1 : a part doubled or laid over another part : PLEAT
2 : something that is folded together or that enfolds
3 a : a bend or flexure produced in rock by forces operative after the depositing or consolidation of the rock b chiefly British : an undulation in the landscape
4 : a margin apparently formed by the doubling upon itself of a flat anatomical structure (as a membrane)
5 : a crease made by folding something (as a newspaper)
fold 3a