diff --git a/src/goals/MergeDuplicates/MergeDupsStep/SenseCardContent.tsx b/src/goals/MergeDuplicates/MergeDupsStep/SenseCardContent.tsx
index 255684ab80..252e431053 100644
--- a/src/goals/MergeDuplicates/MergeDupsStep/SenseCardContent.tsx
+++ b/src/goals/MergeDuplicates/MergeDupsStep/SenseCardContent.tsx
@@ -14,6 +14,7 @@ import { IconButtonWithTooltip, PartOfSpeechButton } from "components/Buttons";
 import MultilineTooltipTitle from "components/MultilineTooltipTitle";
 import DomainChipsGrid from "components/WordCard/DomainChipsGrid";
 import SenseCardText from "components/WordCard/SenseCardText";
+import { combineSenses } from "goals/MergeDuplicates/Redux/reducerUtilities";
 
 interface SenseCardContentProps {
   senses: Sense[];
@@ -31,13 +32,14 @@ export default function SenseCardContent(
 ): ReactElement {
   const { t } = useTranslation();
 
-  const gramInfo = props.senses
-    .map((s) => s.grammaticalInfo)
-    .find((g) => g.catGroup !== GramCatGroup.Unspecified);
-
-  const semDoms = props.senses
-    .flatMap((s) => s.semanticDomains)
-    .sort((a, b) => a.id.localeCompare(b.id));
+  const sense = combineSenses(props.senses);
+  const gramInfo =
+    sense.grammaticalInfo.catGroup === GramCatGroup.Unspecified
+      ? undefined
+      : sense.grammaticalInfo;
+  const semDoms = sense.semanticDomains.sort((a, b) =>
+    a.id.localeCompare(b.id)
+  );
 
   const reasonText = (reason: ProtectReason): string => {
     // Backend/Helper/LiftHelper.cs > GetProtectedReasons(LiftSense sense)
@@ -96,9 +98,9 @@ export default function SenseCardContent(
   };
 
   const protectedWarning =
-    !props.sidebar && props.senses[0].accessibility === Status.Protected;
+    !props.sidebar && sense.accessibility === Status.Protected;
   const tooltipTexts = [t("mergeDups.helpText.protectedSense")];
-  const reasons = props.senses[0]?.protectReasons;
+  const reasons = sense.protectReasons;
   if (reasons?.length) {
     tooltipTexts.push(
       t("mergeDups.helpText.protectedData", {
@@ -114,7 +116,7 @@ export default function SenseCardContent(
       <div style={{ position: "absolute", left: 0, top: 0 }}>
         {gramInfo && (
           <PartOfSpeechButton
-            buttonId={`sense-${props.senses[0].guid}-part-of-speech`}
+            buttonId={`sense-${sense.guid}-part-of-speech`}
             gramInfo={gramInfo}
             onlyIcon
           />
@@ -128,7 +130,7 @@ export default function SenseCardContent(
             side="top"
             size="small"
             text={<MultilineTooltipTitle lines={tooltipTexts} />}
-            buttonId={`sense-${props.senses[0].guid}-protected`}
+            buttonId={`sense-${sense.guid}-protected`}
           />
         )}
       </div>
@@ -144,7 +146,7 @@ export default function SenseCardContent(
         {props.senses.length > 1 && (
           <IconButton
             onClick={props.toggleFunction}
-            id={`sidebar-open-sense-${props.senses[0].guid}`}
+            id={`sidebar-open-sense-${sense.guid}`}
             size="large"
           >
             <ArrowForwardIos />
@@ -152,7 +154,7 @@ export default function SenseCardContent(
         )}
       </div>
       {/* List glosses and (if any) definitions. */}
-      <SenseCardText languages={props.languages} sense={props.senses[0]} />
+      <SenseCardText languages={props.languages} sense={sense} />
       {/* List semantic domains. */}
       <DomainChipsGrid semDoms={semDoms} />
     </CardContent>
diff --git a/src/goals/MergeDuplicates/Redux/reducerUtilities.ts b/src/goals/MergeDuplicates/Redux/reducerUtilities.ts
index d85627d902..719d20c74f 100644
--- a/src/goals/MergeDuplicates/Redux/reducerUtilities.ts
+++ b/src/goals/MergeDuplicates/Redux/reducerUtilities.ts
@@ -12,6 +12,7 @@ import {
 } from "goals/MergeDuplicates/MergeDupsTreeTypes";
 import { newMergeWords } from "goals/MergeDuplicates/MergeDupsTypes";
 import { type Hash } from "types/hash";
+import { newGrammaticalInfo, newSense } from "types/word";
 import { compareFlags } from "utilities/wordUtilities";
 
 // A collection of helper/utility functions only for use in the MergeDupsReducer.
@@ -112,15 +113,42 @@ export function createMergeParent(
 export function combineIntoFirstSense(mergeSenses: MergeTreeSense[]): void {
   // Set the main sense to the first sense (the top one when the sidebar was opened).
   const mainSense = mergeSenses[0].sense;
-  const sep = "; ";
+  const senses: Sense[] = [mainSense];
 
-  // Merge the rest as duplicates.
+  // Mark the rest as duplicates.
   // These were senses dropped into another sense.
   mergeSenses.slice(1).forEach((mergeDupSense) => {
-    const dupSense = mergeDupSense.sense;
-    dupSense.accessibility = Status.Duplicate;
+    mergeDupSense.sense.accessibility = Status.Duplicate;
+    senses.push(mergeDupSense.sense);
+  });
+
+  // Combine the sense content and update the main sense.
+  const combinedSense = combineSenses(senses);
+  mainSense.definitions = combinedSense.definitions;
+  mainSense.glosses = combinedSense.glosses;
+  mainSense.grammaticalInfo = combinedSense.grammaticalInfo;
+  mainSense.semanticDomains = combinedSense.semanticDomains;
+}
+
+/** Create a copy of the first sense with the following content merged from all senses:
+ * definitions, glosses, grammaticalInfo, semanticDomains. */
+export function combineSenses(senses: Sense[]): Sense {
+  if (!senses.length) {
+    return newSense();
+  }
 
-    // Merge the duplicate's definitions into the main sense.
+  const mainSense: Sense = {
+    ...senses[0],
+    definitions: [],
+    glosses: [],
+    grammaticalInfo: newGrammaticalInfo(),
+    semanticDomains: [],
+  };
+
+  const sep = "; ";
+
+  senses.forEach((dupSense) => {
+    // Merge in the definitions.
     dupSense.definitions.forEach((def) => {
       const newText = def.text.trim();
       if (newText) {
@@ -143,7 +171,7 @@ export function combineIntoFirstSense(mergeSenses: MergeTreeSense[]): void {
       }
     });
 
-    // Merge the duplicate's glosses into the main sense.
+    // Merge in the glosses.
     dupSense.glosses.forEach((gloss) => {
       const newDef = gloss.def.trim();
       if (newDef) {
@@ -166,7 +194,7 @@ export function combineIntoFirstSense(mergeSenses: MergeTreeSense[]): void {
       }
     });
 
-    // Use the duplicate's part of speech if not specified in the main sense.
+    // Use the grammatical info if not already specified.
     if (mainSense.grammaticalInfo.catGroup === GramCatGroup.Unspecified) {
       mainSense.grammaticalInfo = { ...dupSense.grammaticalInfo };
     } else if (
@@ -180,11 +208,13 @@ export function combineIntoFirstSense(mergeSenses: MergeTreeSense[]): void {
       }
     }
 
-    // Put the duplicate's domains in the main sense if the id is new.
+    // Merge in the semantic domains.
     dupSense.semanticDomains.forEach((dom) => {
       if (mainSense.semanticDomains.every((d) => d.id !== dom.id)) {
         mainSense.semanticDomains.push({ ...dom });
       }
     });
   });
+
+  return mainSense;
 }