A common Arabic term for jinn-possession is mass (مَسٌّ). The one possessed is called mamsus (مَمْسُوسٌ).
Another term used for possession is sar' (صَرْعٌ) whilst the possessed is called masru' (مَصْرُوعٌ). However, this word is also applied for biologically caused fits and epilepsy.
Types of possession
In the experience of Raqis (Muslim exorcists), jinn-possession of humans take a variety of forms. Possession may be partial, affecting only certain parts of the body, or it may be complete, affecting the whole body and consciousness. Possession may also be temporary (in effect for a short period of time) or long lasting (in effect for an indefinite or long period).
Some scholars including Ibn Taymiyyah affirm that jinn can also possess inanimate objects like plants and rocks.
Reasons for possession
Common reasons for possession are:
Lust on the jinni’s end. It is attracted or in love with the person.
Jest, mischief or plain evil on part of the jinni.
Retaliation for a wrong or harm caused to it by the person.
Sihr (black magic). Magician contracted a jinni on the person.
Evil eye. The devils play a part in the effect of evil eye on the victim.
In the view of Raqis, the people most vulnerable to jinn-possession are those who are irreligious and negligent of preventive measures prescribed by the Prophet (ﷺ).
Symptoms of possession
There are many symptoms of jinn-possession. The possessed will typically only display some of them.
There are four categories of jinn-possession symptoms (this article does not list all the symptoms of possession):
Personality changes like rapid mood shifts (sudden inexplicable laughter, anger or crying ), persistent feelings of sadness, low-spirits, complete change of character.
Physical abnormalities like chronic pains/bruises/illnesses that have no clear medical explanation or successful medical treatment.
Mental abnormalities like frequent nightmares, blasphemous whisperings, insomnia.
Spiritual changes like sudden abandonment of religious practices, or absurd reaction to Quranic recitation (ruqya) such as crying and foaming of the mouth, or an adverse reaction when making physical contact with liquids on which the Quran was recited.
Most symptoms of jinn-possession are also found in cases of sihr, evil eye and biological illnesses. Subsequently, not everyone that displays those symptoms is possessed. Symptoms are indicative and the true nature of their cause can only be determined through investigation, and jinn-possession therefore can be determined through recitation and a ruqya diagnosis.