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SynAc
Term

hacker

An unauthorized user who attempts to or gains access to an information system.

Senses

Sense 1

An unauthorized user who attempts to or gains access to an information system.

References
  • NICCS (CISA) Cybersecurity VocabularyJan 06, 2026
    NICCS glossary export (CSV)
    https://niccs.cisa.gov/rest/vocab/export-csv
    NICCS is a CISA (DHS) program. Individual glossary entries include a "From" attribution (e.g., CNSSI 4009, NIST SPs, NICE Framework). Treat "From" values as upstream provenance and verify before quoting large portions of text.
    Source: NICCS (CISA) Cybersecurity Vocabulary (niccs.cisa.gov).
1 (I)

Someone with a strong interest in computers, who enjoys learning about them, programming them, and experimenting and otherwise working with them. (See: hack. Compare: adversary, cracker, intruder.)

Usage: This first definition is the original meaning of the term (circa 1960); it then had a neutral or positive connotation of "someone who figures things out and makes something cool happen".

References
  • IETF RFC 4949 (Internet Security Glossary)Jan 06, 2026
    RFC 4949 — Internet Security Glossary (Version 2)
    https://www.rfc-editor.org/rfc/rfc4949.txt
    RFC 4949 is published by the IETF Trust and marked as "Distribution of this memo is unlimited". Verify IETF Trust copyright/licensing terms for reuse.
    Source: IETF RFC 4949 (rfc-editor.org).
2 (O)

"An individual who spends an inordinate amount of time working on computer systems for other than professional purposes." [NCSSG]

References
  • IETF RFC 4949 (Internet Security Glossary)Jan 06, 2026
    RFC 4949 — Internet Security Glossary (Version 2)
    https://www.rfc-editor.org/rfc/rfc4949.txt
    RFC 4949 is published by the IETF Trust and marked as "Distribution of this memo is unlimited". Verify IETF Trust copyright/licensing terms for reuse.
    Source: IETF RFC 4949 (rfc-editor.org).
3 (D)

Synonym for "cracker".

Deprecated Usage: Today, the term is frequently (mis)used (especially by journalists) with definition 3.

References
  • IETF RFC 4949 (Internet Security Glossary)Jan 06, 2026
    RFC 4949 — Internet Security Glossary (Version 2)
    https://www.rfc-editor.org/rfc/rfc4949.txt
    RFC 4949 is published by the IETF Trust and marked as "Distribution of this memo is unlimited". Verify IETF Trust copyright/licensing terms for reuse.
    Source: IETF RFC 4949 (rfc-editor.org).