Glossary
Re-Identification
Re-identification recovers a specific individual's identity from data that was intended to be anonymous, often not by breaking any single technical protection directly but by combining the anonymized data with other, seemingly unrelated external information that, together, narrows down to one specific person. A dataset can satisfy every technical anonymization requirement applied to it in isolation and still be re-identifiable once cross-referenced against something else entirely.
This is why anonymization can't be treated as a permanent, one-time property established at the moment data is anonymized — new external datasets that make re-identification newly possible can appear well after the original anonymization was considered adequate, which means access to anonymized data still warrants some ongoing scrutiny rather than being treated as permanently and completely safe.