Straitjacket: Or strait-jacket or strait jacket. 1. A garment shaped like a jacket with long sleeves the ends of which can be tied behind the back to restrain a violently disturbed person, as in a psychiatric in-patient unit, so that the person does not injure themselves or anyone else. (The straitjacket has also seen use in prisons, escapology, and sexual bondage.) At the present time, straitjackets are not utilized in the inpatient settings 2. By extension, anything that is constricting, restricting, very limiting, confining. Sometimes spelled straightjacket, straight-jacket, or straight jacket. However, strait means narrow or confined so that straitjacket is preferable. Also called a camisole.