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Terms and Definitions

Dissociative Identity Disorder Terminology

This Dissociative Identity Disorder terminology list was partly compiled with some references to did-research.org and via personal experience or interaction with the DID community. These terms and definitions are not exhaustive, and we will continue building this resource.

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Abusive Introject

An alter that is based on someone involved with their trauma experienced. They may or may not see themselves as the individual they represent and may play the role of a persecutor.

Age Slider

An alter that can present as different ages, sometimes within certain ranges or specific ages, sometimes with a different appearance, personality, job or set of memories associated with each age.


A dissociated self-state with their own age, gender, sexuality, perceived appearance, wants, needs, desires, opinions, memories, skills, abilities and even psychological disorders and physiological reactions. May also be referred to as Headmates, System Mates, Others, or Parts.

Amnesia Barriers

A loss of memory, whether partial or complete, that blocks an alter, usually the host, from remembering a traumatic experience.

Apparently Normal Part

ANP are rational, present-oriented and grounded alters that handle aspects of daily life. Includes social interaction and attachment, taking care of others, work, play, exploration, learning and caring for physical needs. They usually display avoidant behaviour towards reminders of their trauma or stress, such as amnesia, dissociation or numbing out emotional intensity.


A term for an alter of adult age; usually used by littles in the context of someone who looks out for them. Ex. "That's my Big," or "My Big told me..."


Describing oneself as feeling blendy is associated with being unsure of which of themselves they are. The person may feel like two or more alters at once, which creates a feeling of confusion on where the identity of one alter starts and another begins.


An alter that looks after younger, weaker or more vulnerable alters or an external individual responsible for a child’s wellbeing.


A state in which two or more alters are present in or using the body at once or are aware of the outside world simultaneously. Alters may have varying degrees of control when co-conscious and may be aware of each other and each other’s thoughts to varying degrees, depending on the alter and the system. This term is often shortened to co-con.


A specific type of co-consciousness in which two or more alters are in control of the body at the same time to varying degrees. Alters may be aware of one another or own each other’s actions to varying degrees depending on the alters, the system and the situation.

Covert System

A system in which switches or the differences between alters are not obvious, so only people who know them well can tell when someone else is fronting. It is easy to mistake these systems as being rarer as they are seen less frequently, but this isn’t the case.


An internal disconnect from one’s thoughts, feelings, memories, history, body or actions or between one and one’s surroundings that manifests as a sense of unreality or as slowed, fuzzy, nonsensical or disjointed thoughts, emotions or actions. This is a key symptom of dissociative disorders, but can also be experienced by those with other psychological disorders or mental health concerns, relating to trauma or otherwise.

Dissociative Amnesia

A state of unawareness or forgetfulness of varying periods of time that cannot be accounted for by ordinary memory processes. It is also a dissociative disorder that covers different degrees of amnesia.

Dissociative Fugue

One or more episodes of amnesia involving memories, personality and other identifying characteristics of individuality. It can last for an extended period, usually involves unplanned travel or wandering, and is sometimes accompanied by establishing a new identity.

Emotional Part (EP)

The parts of the personality that represent the dissociation or contain the traumatic materials drawn forth by reminders of the trauma. They can be experienced as various aspects of dissociative flashbacks or negative emotions and are often unaware of the present. Despite this, they may still handle some daily life functions in some cases.

Emotional Protector

An alter whose role in the system is to take emotional abuse or comfort other alters to soften the effects of emotional trauma.

Factive Introject

An alter with the form, personality, and possibly the psychological backstory e.g. memories of an outer-world person, whether a relative, a celebrity, an abuser or even an acquaintance.

Fictive Introject

An alter with the form, personality, and possibly the psychological backstory, e.g. memories of a fictional character. It is important to note that as this system member develops, they can deviate from the source character. So, they should not be treated as if they are that character, especially not in an idolizing manner.

Floaty, Fuzzy

The words floaty or fuzzy are often used to describe the feeling related to dissociating. This can be like a floaty feeling inside the head, which is generally an unpleasant sensation.


An alter that is not fully differentiated or developed and may represent a single function, memory, emotion or idea.


An alter or group of alters that frequently use the body and are responsible for daily life.


The process of switching, becoming the person at the helm of the body, so to speak. The alter at the front is aware of the outside world and interacts using the body on a conscious level.

Functional Multiplicity

To achieve functional multiplicity is to integrate to the point of having less amnesia barriers and increased communication between alters. This is often a goal to function in day to day life while remaining a system of alters, and together, as one whole.

Fusion, Fuse

Through the use of integration, there are some systems who choose to pursue fusion, which is to become one cohesive self. Two or more alters within a system can fuse, or if someone experiences final fusion, the theory is that they are no longer multiple selves and live as an individual.


An alter that controls switching, access to the front, access to certain areas of the inner world or access to certain alters or memories. May or may not also serve as an internal self-helper or even the caretaker at times.

Headspace/Inner World

An internal manifestation in which alters reside and can interact when not present in or using the body. Can range from a single room to an entire town or supposed world.


The Host is the alter who is fronting the most often. The host can change from one to another, depending on time periods. Due to a misconception that Internal Family Systems is for DID, some perceive there to be a "Core" person, however, all self states are alters to each other, including the host.


Integration refers to the breaking down of amnesia barriers or dissociative walls in communication. Integration is progress in or awareness of each other, which can involve hearing each other, feeling each others feelings, or finding alternative ways to communicate.

Internal Self-Helper (ISH)

An alter that holds vast amounts of knowledge about the system, alters, trauma and/or internal workings. They may or may not also function as a gatekeeper for the system alongside this.


A term for a child alter. Their presentation and manner of speaking reflects their young internal age. They may feel small and out of place in an adult body. Despite their age level, Littles are more aware of the world than children are.

Memory Holder

An alter that holds memories that are usually traumatic in nature. However, memories are sometimes related to childhood innocence or a caring family that could not be seen in the same light as if the memories were accessible at the same time as memories regarding abuse.

Micro Switching

Micro switching describes very quick switches that can be a word, a sentence, or even an expression, then returning to the previous alter.


A term for a pre-adolescent age alter. Some definitions place Middles between the ages of 8 and 11, though some people with DID hold varying viewpoints on this range.

Non-Human Alter

An alter that presents as an animal or fantasy creature due to their formative environment, specific traumas, function, purpose or disposition.

Non Playable Character (NPC)

An NPC is not an alter, but is the imagined product of the need of an alter. The host of a system will not hear the voice of the NPC within the headspace like they would one of their alters. The NPC allows unmet needs to be fulfilled, such as interacting with a significant other, a child, or even a pet.

Overt System

An overt system experiences switches between self states that are more obvious. The differences between alters are more pronounced and more difficult to brush off as a quirk. Only approx. 6 percent of systems are considered overt.

Owned Thoughts, Actions, Feelings

An "Owned" thought, action, or feeling is one that the person with DID identifies with as their own, rather than belonging to another self state.

Passive Influence

Passive influence is the experience of one alter influencing the host, or whoever is fronting, in actions, words, thoughts, or way of speaking. This differs from the term "Blendy" in that this feels less like there is a duality of alters and more like being ones-self while experiencing the influence of another.


A persecutor holds more anger and can exhibit more self-damaging behaviours, which can be to sabotage the host or their healing.

Physical Protector

Physical protectors might become aggressive in presentation or try to prevent physical trauma via self-defence.


A person who is polyfragmented has 100 alters or more; many of which can be fragments.


Protectors are alters that protect the body, the system, host, or other specific alters from experiences they hope to shield the others from. Protectors might feel more equipped or confident in being assertive when others may not.

Rapid Switching

Rapid switching can be described like a rolodex of several short consecutive switches between different alters.

Sexual Alter

Sexual alters may be created to handle specific forms of trauma, and to keep that knowledge away from other parts.

Somatic Symptoms

Somatic symptoms are physical symptoms that are due to sources of stress and impairment. An example of this concept is when we experience a headache or stomach ache due to high anxiety. These symptoms cannot be explained within the medical system, though, their sources are linked to duress such as childhood trauma.


A subsystem is a system within a system. There are two types of subsystems. The first one is an alter with their own alters. The second type is a group of alters who are not in contact with the main system. They aren't dormant, but are not in contact or communication.

The Surface

The surface is a metaphor to describe being the alter in control of the body. This indicates not being inside the mind, but on the surface of consciousness.


When one alter stops fronting or "being in control" of the body, and a different alter fronts in their place.


The entire collection of alters within one body. Also known as a Household, Collective, Clan, or Crew.

System Name

Some systems have a name to refer to the entirety of their system. This is comparable to saying that a person is a member of a specific city. (New Yorker)

System Role

Some system roles can be protectors, persecutors, gatekeepers, memory holders, hosts, Littles, Middles, Teens... etc. Roles, even that of the host, can change over time.


An alter in their teen years.


A trigger to switch can be positive or negative. An example of a positive trigger is something that an alter likes, such as seeing candy or a toy followed by a Little fronting. A negative trigger can be a memory or present occurrence where another alter may be more equipped to handle the situation and comes to the surface.


Visions of seeing alters can sometimes be perceived as hallucinating. Seeing alters is less common than hearing them and are the result of dissociative experiences. Some describe this like a projection of their alters in the room in front of them.


Some people with DID hear the voices of the alters inside of their heads. Some hear children laughing or crying. They may pick up specific words, which can often be one alter speaking to another.