The term 'Threshold Adjoiner' is a job description for a JAMB, which is a four-letter word. A JAMB is a type of door or window frame that is used to support the structure and provide a seal between the door or window and the wall. The Threshold Adjoiner is responsible for installing the JAMB and ensuring that it is properly secured and sealed. They must also ensure that the threshold is level and properly aligned with the door or window frame. The Threshold Adjoiner must have a good understanding of carpentry and construction techniques in order to properly install the JAMB and ensure that it is secure and properly sealed.