Fingerprints

Plain Arch

Ridges enter from one side of the pattern and flow or tend to flow out to the other side with a slight rise or wave in the center.

Tented Arch

Most of the ridges enter on one side of the fingerprint and flow out or tend to flow out the other side: however, the ridges at the center form an angle, an up thrust, or possess two of the basic characteristics of a loop, lacking the third.

Loop

One or more of the ridges enter on one side of the pattern, recurve, touch or press an imaginary line between delta and core, and flow out or tend to flow out on the same side from which they entered.

Whorl

Consists of one or more ridges that make a complete circuit, with two deltas, between which, when an imaginary line is drawn, at least one recurving ridge is cut or touched.

Central Pocket Loop 

Consists of at least one recurving ridge, or an obstruction at right angles to the direction in which the pattern flows. It has two deltas, between which, when an imaginary line is drawn, no recurving ridge within the pattern area is cut or touched.

Lateral Pocket Loop

Consists of at least one recurving ridge, which flows into a pocket formation of ridges, and flows out or tends to flow out from the same side from which they entered.

It has one delta.

Twinned (Double) Loop

consists of two separate loop formations with two deltas.

Accidental

Contains two or more distinct types of patterns with the exception of the plain arch, with two or more deltas, or a pattern that has some of the requirements for two or more different types, or a pattern that conforms to none of the definitions.