Crinkle-cut

Crinkle-cutting is slicing that leaves a corrugated surface. This is done with corrugated knives or mandoline blades.

Crinkle-cut potato chips are sometimes called ruffled, by analogy with a ruffle in sewing. French fries or sweet potato fries may also be crinkle-cut, and may be called "wavy fries".

If the potato is turned 90° between cuts, the result is waffle fries.

Pommes gaufrettes, waffle fries, or criss-cross fries are crisps obtained by quarter-turning the potato before each pass over the corrugated blade of a mandoline and deep-frying.

Ruffled potato chips

Sweet potato fries or "wavy fries"

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Wikipedia