Lock body (case)The rectangular case that sits inside the door.
DeadboltThrown by the key or the thumbturn once the door is shut.
Latch boltSpring-loaded; its angled face lets the door latch as it shuts.
StrikeFixed to the frame; the bolts go into its openings.
LeverDraws back the latch bolt; one per side of the door.
Mortise cylinderThe keyed cylinder, set apart from the lever.
In the door's edge 3
Armor front (faceplate)Covers the front of the case; the bolts pass through it.
Auxiliary latch (deadlatch)Guards the latch bolt against being pushed back.
Mortise (pocket)The pocket cut in the door's edge that the lock sits in.
The trim 3
ThumbturnThrows and draws back the deadbolt from inside, without a key.
EscutcheonThe plate behind the lever, one on each face of the door.
SpindlePasses through the lock body and turns with the lever.
How this list was compiled: Read 2026-09-30; a name is kept only where two of these use it. (1) A lock maker's three guides, https://www.pdqlocks.com/blog/how-to-identify-a-mortise-lock and the two listed with it: a rectangular lock body or case in a pocket (the mortise) cut in the door's edge; the armor front or faceplate on the door edge; latchbolt, deadbolt and auxiliary latch in one case; lever, escutcheon or sectional trim; a cylinder set apart from the lever; thumbturn; lever spindle; strike. (2) A second lock maker's mortise lock cut sheet and function chart, https://www.townsteel.com/support/product-documents/mrx-l-cut-sheet : faceplate, strike, lever, escutcheon, latch bolt operated by the lever from either side, dead bolt projected by key from outside and by the thumb turn (turn piece) from inside, auxiliary dead latch, cylinder. (3) Wikipedia, Mortise lock (lock body, lock trim, strike plate or box keep, keyed cylinder, the pocket cut in the door's edge), Lockset (spring-loaded latch bolt with an angled surface; the guardbolt that prevents unwanted retraction of the latch bolt; deadbolt; thumbturn; escutcheon) and Door handle (the spindle the handle turns). (4) Steel Door Institute glossary, https://steeldoor.org/glossary/ : mortise lock, strike. Licence: own work
The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's lock, nothing traced. Licence: own work
How it works
A mortise lock sits in a pocket cut in the door's edge. These are the parts of a mortise lock, often sold as a lockset: the lock body and bolts, the strike, and the trim on each face.
Read the full guide
In the door's edge
The mortise is the pocket cut in the door's edge, and the lock body sits in it. The armor front is the plate you see on the door's edge. Through it come the deadbolt, the latch bolt and, on many locks, a small auxiliary latch.
On the faces of the door
An escutcheon on each side carries a lever, and a spindle joins the levers through the lock body. The key goes in the mortise cylinder outside. The thumbturn inside moves the deadbolt without a key.
To tell a mortise lock at a glance: a long plate on the door's edge, and a key cylinder set apart from the lever.
Questions and answers
What are the parts of a mortise lockset called?
The lock body or case, the armor front on the door's edge, the latch bolt, the deadbolt, often an auxiliary latch, the strike on the frame, and the trim: escutcheons, levers on a spindle, a mortise cylinder and a thumbturn.
What is the difference between the latch bolt and the deadbolt?
The latch bolt is spring-loaded with a slanted end, so it clicks shut as the door closes, and the lever draws it back. The deadbolt has a square end and only moves when you turn the key or the thumbturn.
What is the plate on the edge of the door called?
The armor front, also called the faceplate. It covers the front of the lock body, and the bolts pass through it. The plate on the frame that the bolts go into is the strike.
Why is it called a mortise lock?
Because the lock body is set into a mortise, a pocket cut in the door's edge, where other locks are fitted through holes bored in the door's face.