Crinkle-cutting means cutting so the result is corrugated

Corrugated

The term corrugated, describing a series of parallel ridges and furrows, may refer to the following:*Corrugated fiberboard also called corrugated cardboard*Corrugated galvanised iron*Corrugated plastic*Corrugated Frog...

 (forms regular waves). One can do this with specialized knives or mandoline

Mandoline

A mandoline is a cooking utensil used for slicing and for cutting juliennes; with suitable attachments, it can make crinkle-cuts. It consists of two parallel working surfaces, one of which can be adjusted in height. A food item is slid along the adjustable surface until it reaches a blade mounted...

. It is frequently used for potato chips, and (in that context especially) is also referred to as ruffled, by analogy with the ruffle

Ruffle

In sewing and dressmaking, a ruffle, frill, or furbelow is a strip of fabric, lace or ribbon tightly gathered or pleated on one edge and applied to a garment, bedding, or other textile as a form of trimming...

, a strip of fabric often gathered

Gather (sewing)

Gathering is a sewing technique for shortening the length of a strip of fabric so that the longer piece can be attached to a shorter piece. It is commonly used in clothing to manage fullness, as when a full sleeve is attached to the armscye or cuff of a shirt, or when a skirt is attached to a...

, creating regular folds. It is also commonly used for french fries

French fries

French fries , chips, fries, or French-fried potatoes are strips of deep-fried potato. North Americans tend to refer to any pieces of deep-fried potatoes as fries or French fries, while in the United Kingdom, Australia, Ireland and New Zealand, long, thinly cut slices of deep-fried potatoes are...

.