Salpetriere School -
Salpetriere school of hypnosis. A school of psychopathology operated by J. M. Charcot, who's views on hypnosis influenced Sigmund Freud. Charcot believed that hypnosis was due to a form of hysteria. 
Schizophrenia -
A serious mental disorder which affects the sufferers ability to deal with reality. Usually ascribed to dissociation, splitting of consciousness.
Script -
In hypnosis this term is usually used to describe a pre-prepared induction or deepener. 
Secondary Gain -
Every cloud has a silver lining! Nobody really wants a problem but sometimes a problem can have a small advantage attached to it and it is this advantage that is described by the term secondary gain. For example, no-one wants a painful headache but it may have the secondary gain benefit of getting some attention. 
Selective Amnesia -
Inability to recall memories about a specific thing. Often used as a demonstration of hypnotic phenomena where a subject might be told to forget a number between one and five and then asked to count the fingers on his hand!
Selective attention -
The natural ability of people to select which incoming information they will consciously receive. We perceive much more than we realize but something within us decides what is important to notice. Normally an unconscious process it can be temporarily explored consciously. The manipulation of selective attention is thought to be important to achieving a hypnotic state. 
Self Hypnosis -
Where a person enters a hypnotic state under their own guidance, without using an external hypnotist. Also called auto-hypnosis.
Signalling -
Usually called ideo-motor response signalling (IMR). Where a small bodily movement is used for communication.
Sitophobia -
Irrational fear of food.
Shyness -
A feeling of unease when receiving attention from others. Often accompanied by blushing. Usually due to conditioning and quite treatable with hypnosis.
Sleep Walking -
Also called Somnambulism, see below.
Somnambulism -
Literally sleep walking. Usually occurs in children as a modification of natural dream sleep. The subject walks in the dream state and usually has no recollection of it after awakening. In hypnosis the term refers to a deep trance state in which  subjects can open their eyes and even perform quite complex tasks without breaking the state. Amnesia and hallucination are possible.
State Dependent Memory -
Refers to memories which are dependent upon the replication of certain physiological 'contexts' before they can be recalled. For example, an event that takes place while the subject is heavily intoxicated or in a state of high emotion might be forgotten upon return to normality and can be recalled only when the non ordinary state is re-experienced. To a certain extent all memory can be said to be state dependent but fortunately for most people 'normal consciousness' is a  steady state.
Stress -
Stress occurs in any organism provoked into making a survival decision or taking a survival action (be this fight or flight). So it can be seen that stress is not an unnatural phenomenon but actually a necessity of survival in much of the animal kingdom. This survival stress is usually short lived as the needed action (fight or flight) can be taken and the bodily state allowed to return to normal. The many chemicals needed to produce the stress state in the body and brain (to maximize functionality) can disperse. Alas, due to the complex nature of the human animal and human society the 'primitive' instincts to survival action are regularly triggered, but usually without the availability of a survival response. That is, although a person often comes under the impulse to fight or flee, either action is usually inappropriate. Thus stresses build up in the body and can lead to many kinds of dysfunction if not successfully controlled or dissipated.
Subconscious -
Mental processes that are not normally conscious, separate from consciousness. The word is often interchanged loosely with unconscious.
Subliminal -
This literally means - below the threshold of sensory awareness
Suggestibility -
Defines the extent to which a person will accept a proposal to be factual. 
Suggestion -
A proposal made to a person as fact, usually just before or during the hypnotic state. The purpose of which is usually to obtain a deeper hypnotic state, increase suggestibility or obtain some therapeutic change.