What does jamb mean?
A jamb is the vertical side of a doorway or window opening, or the upright member of a door or window frame. It is especially useful when describing repairs, construction, or the way a door or window fits: a swollen jamb can make a door scrape, stick, or fail to close properly, while a damaged window jamb may need to be repaired or replaced. The word is recognized in both British and American English, although some speakers say doorpost or sidepost more often. Its origin reflects an older visual idea: the word ultimately comes through Old French jambe, meaning “leg,” because the upright supports of an opening could be imagined as the structure's legs. Jamb also survives as a rare verb meaning to squeeze, press, or become wedged, but that usage is largely archaic or regional. In contemporary usage, jamb is concise and precise architectural vocabulary.
A vertical side of a doorway or window opening, especially an upright member of a door or window frame.
"The builder replaced the damaged jamb before installing the new door."
Common in architectural, construction, and property-maintenance contexts in British and American English.
To press, crush, or become wedged; to jam.
"The heavy gate jambed against the post."
Rare and chiefly archaic or regional in modern English.
The standard plural is jambs; constructions such as "door jambs" and "window jambs" are common.
"The renovation team repaired both door jambs."
A jamb is the doorway's upright "leg"—the word itself comes from French for leg.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of jamb
English jamb came through Middle English from an Anglo-French form meaning a side post or the side of an opening. It ultimately derives from Old French jambe, “leg,” from Latin gamba, “leg,” reflecting the upright posts that supported the sides of a doorway. The same Latin root is reflected in related forms such as gambit and gambol through Italian and French.
Related word forms
How jamb is actually used
In modern standard English, jamb is primarily an architectural term and is used in both British and American English. The verb jamb, meaning to press, crush, or become wedged, is rare, archaic, or regional.
Easily confused with jamb
A jamb is a vertical side of a doorway or window frame, whereas a jam is something wedged in place, a crowded condition, or a fruit preserve.
A jamb is a vertical side member of a doorway or window opening; a lintel is the horizontal member above it.