O5 — The capital letter "o", not the number zero. The O5 Council, which is either the "Council of Observers, Level 5" or "Overseer Level 5 Council" (depending on who you ask) is the highest authority in the Foundation, a council of 12 or 13 individuals who have the power to authorize or veto any action taken by the Foundation as a whole. O5 Council members are only known by their numbers (O5-1 through O5-13) and typically are not allowed to contact SCP objects or entities directly for fear of contamination.
Addendum — (Plural: addenda.) An additional section of a SCP article that either expands on specific aspects of the primary Description, shows a progression of information over time, or otherwise provides additional insight that does not fit into the Description block. All test logs, interviews, and exploratory information are generally written as addenda.
agent — An undercover field agent of the Foundation, typically capitalized when used as a title (e.g. Field Agent Smith). Note that not all field personnel employed by the Foundation are necessarily "agents" in this sense, nor do all such personnel have the title "Agent". See also: containment team, response team, Mobile Task Force, and researcher.
amnestic — Also referred to as an "amnesiac" in older articles, these are drugs, procedures, or devices that induce memory loss when administered to an individual. These are often used to wipe the memories of civilian witnesses to maintain deniability of Foundation operations.
Clarification: "amnestic" is the scientific, dictionary term for something that induces memory loss. The dictionary definition of "amnesiac" is a person with amnesia. While many site members will passionately argue their right to use that term in their writing, only one is scientifically correct.
cognitohazard — A term used to refer to objects that are dangerous to sense or perceive, whether through sight, sound, smell, taste, or feeling (not necessarily simply by touch).
containment team — A team of field personnel who specialize in recovering or retrieving anomalous objects or entities. Containment team members may or may not be field agents as well, but usually have a different title, such as "Containment Specialist". See also agent, response team.
[DATA EXPUNGED] — One of the two types of censorship used on the site, something that is "expunged" has been permanently deleted from all records because the information poses a hazard in and of itself, such as if it's a memetic hazard. Should always be in all-caps with square brackets. See also [REDACTED].
Decommissioned — A sub-class of object that has been intentionally destroyed. Out-of-universe, a type of object that was so egregiously bad that it has been destroyed by staff members and kept around as a sort of "hall of shame". See also Neutralized and the Object Classes guide for more information.
Description — The section of a SCP article that explains how to unambiguously identify the object or entity in question and explains in a clear and concise way what it does and why it is contained. The basic description can be enhanced by one or more addenda, but you should be able to understand its basic function through the Description alone.
doctor — A term used to refer to a person who is either a holder of a Doctor of Philosophy (PhD) degree or a professional medical doctor, often incorrectly used. While both of the above are entitled to use the title "Dr." in their name (e.g. "Dr. Mackenzie"), only the latter should be referred to as "a doctor"; the former is "a biologist", "a chemist", "a physicist", or more broadly "a researcher".
Euclid — A primary Object Class that describes an item or entity that is either unpredictable or otherwise insufficiently well-understood as to be reliably contained. Many consider this the "default" classification for new objects until such time that they are better understood or determined to be more dangerous than previously thought. Many consider any sentient and/or sapient entity to be automatically Euclid rather than Safe due to the fact that any entity with a mind of its own can always choose to stop cooperating with us. Named after a famous mathematician. See Object Classes for more information.
Explained — A sub-class of object that has either been debunked as a hoax, sufficiently understood so as to be normal scientific knowledge, or so widely disseminated that containment is no longer possible.
infohazard — A term used to refer to objects that are dangerous to know about. Differs from cognitohazards in that cognitohazards require direct contact whereas infohazards may spread simply through people telling each other about them.
Keter — A primary Object Class that describes an item or entity that either cannot be reliably contained or otherwise poses an inimical threat to humanity. Keter-class objects and entities are highly dangerous and have extremely complex containment procedures. Named after the topmost of the Sephirot in the Jewish Kabbalah. See Object Classes for more information.
memetic — A concept that is sufficiently complex as to require its own essay (Understanding Memetics), memetics are a sub-class of cognitohazards that deal with transfer of information. In particular, anomalous memetic agents are bits of hazardous information that are like a mental virus, triggering anomalous reactions in people who are exposed to them. It should not be used colloquially for "mind-affecting", even though most memetic agents are indeed mind-affecting.
Mobile Task Force — A Mobile Task Force (or MTF for short) is a highly-trained and specialized team that is deployed to various locations as needed to deal with specialized threats or conditions. Mobile Task Forces are designated by a Greek letter and a number (e.g. "MTF Alpha-7", "MTF Omega-15") and may have a nickname attached, similar to many real-life military units. MTFs are the elite personnel of the Foundation, and run the gamut from highly experienced field researchers to combat-hardened troops.
Neutralized — A sub-class of object that has been destroyed or otherwise rendered non-anomalous. See Object Classes for more information.
Object Class — Also known as the Safe/Euclid/Keter (S/E/K) category, a system of categorization based roughly on the difficulty of containment for an item. See box test below or the Object Classes guide for more information.
[REDACTED] — One of the two types of censorship used on the site, something that is "redacted" is withheld from the article because the reader is not cleared to see the information, typically because it's of a higher clearance level. Should always be in all-caps with square brackets. See also [DATA EXPUNGED].
researcher — A broad term for anyone involved in research and development at the Foundation. Researchers can be involved in anything from figuring out how an anomalous object or entity functions to developing better materials and containment procedures. Field researchers may also accompany containment teams to better assess the nature of an uncontained anomaly in real-time.
response team — A heavily armed team trained to deal with security or containment breaches, typically at a secure Foundation site. Response team members are also sent into the field to escort containment teams when dealing with highly hostile or dangerous objects or entities, or when enemy Groups of Interest are involved.
Safe — A primary Object Class that describes an item that is sufficiently well-understood that it can be reliably contained with little to no risk. As famously stated, a Safe object can still very much be dangerous; a thermonuclear warhead in real life would be considered Safe as it cannot detonate unless multiple safety interlocks are removed. See Object Classes for more information.
Thaumiel — An esoteric Object Class that describes an item that either counteracts or neutralizes the effect of other, particularly Keter-class,