fingerprint

(noun) a print made by an impression of the ridges in the skin of a finger; often used for biometric identification in criminal investigations.

(noun) a generic term for any identifying characteristic. Example: "That tax bill had the senator's fingerprints all over it."

(noun) a smudge made by a (dirty) finger. Synonyms: fingermark.

(verb) take an impression of a person's fingerprints.