diff --git a/resources/definitions/fdmprinter.def.json b/resources/definitions/fdmprinter.def.json
index 458c97af00..986891857f 100644
--- a/resources/definitions/fdmprinter.def.json
+++ b/resources/definitions/fdmprinter.def.json
@@ -398,6 +398,27 @@
                     "settable_per_extruder": false,
                     "settable_per_meshgroup": false
                 },
+                "machine_extruders_share_nozzle":
+                {
+                    "label": "Extruders Share Nozzle",
+                    "description": "Whether the extruders share a single nozzle rather than each extruder having its own nozzle. When set to true, it is expected that the printer-start gcode script properly sets up all extruders in an initial retraction state that is known and mutually compatible (either zero or one filament not retracted); in that case the initial retraction status is described, per extruder, by the 'machine_extruders_shared_nozzle_initial_retraction' parameter.",
+                    "type": "bool",
+                    "default_value": false,
+                    "settable_per_mesh": false,
+                    "settable_per_extruder": false,
+                    "settable_per_meshgroup": false
+                },
+                "machine_extruders_shared_nozzle_initial_retraction":
+                {
+                    "label": "Shared nozzle initial retraction",
+                    "description": "How much the filament of each extruder is assumed to have been retracted from the shared nozzle tip at the completion of the printer-start gcode script; the value should be equal to or greater than the length of the common part of the nozzle's ducts.",
+                    "unit": "mm",
+                    "default_value": 0,
+                    "type": "float",
+                    "settable_per_mesh": false,
+                    "settable_per_extruder": true,
+                    "settable_per_meshgroup": false
+                },
                 "machine_disallowed_areas":
                 {
                     "label": "Disallowed Areas",