(n.) The jamb or sidepiece of a doorway.

French door Samson post archway back door baluster balustrade banister barway bulkhead carriage entrance cellar door cellarway door doorjamb doorway front door gate gatepost gateway hatch hatchway hitching post jamb king post lintel milepost mullion porch portal porte cochere post postern propylaeum pylon scuttle side door signpost snubbing post stanchion standard stile storm door threshold tollgate trap trap door turnpike turnstile upright