diff --git a/server/src/main/java/org/opensearch/action/support/master/MasterNodeRequest.java b/server/src/main/java/org/opensearch/action/support/master/MasterNodeRequest.java
index d5be6c48e23b8..55d5048f14d13 100644
--- a/server/src/main/java/org/opensearch/action/support/master/MasterNodeRequest.java
+++ b/server/src/main/java/org/opensearch/action/support/master/MasterNodeRequest.java
@@ -44,9 +44,15 @@
  */
 public abstract class MasterNodeRequest<Request extends MasterNodeRequest<Request>> extends ActionRequest {
 
+    /**
+     * @deprecated As of 2.0, because promoting inclusive language, replaced by {@link #DEFAULT_CLUSTER_MANAGER_NODE_TIMEOUT}
+     */
+    @Deprecated
     public static final TimeValue DEFAULT_MASTER_NODE_TIMEOUT = TimeValue.timeValueSeconds(30);
 
-    protected TimeValue masterNodeTimeout = DEFAULT_MASTER_NODE_TIMEOUT;
+    public static final TimeValue DEFAULT_CLUSTER_MANAGER_NODE_TIMEOUT = TimeValue.timeValueSeconds(30);
+
+    protected TimeValue masterNodeTimeout = DEFAULT_CLUSTER_MANAGER_NODE_TIMEOUT;
 
     protected MasterNodeRequest() {}
 
@@ -63,21 +69,49 @@ public void writeTo(StreamOutput out) throws IOException {
 
     /**
      * A timeout value in case the master has not been discovered yet or disconnected.
+     * @deprecated As of 2.0, because promoting inclusive language, replaced by {@link #clusterManagerNodeTimeout}
      */
+    @Deprecated
     @SuppressWarnings("unchecked")
     public final Request masterNodeTimeout(TimeValue timeout) {
         this.masterNodeTimeout = timeout;
         return (Request) this;
     }
 
+    /**
+     * A timeout value in case the cluster manager has not been discovered yet or disconnected.
+     */
+    @SuppressWarnings("unchecked")
+    public final Request clusterManagerNodeTimeout(TimeValue timeout) {
+        this.masterNodeTimeout = timeout;
+        return (Request) this;
+    }
+
     /**
      * A timeout value in case the master has not been discovered yet or disconnected.
+     * @deprecated As of 2.0, because promoting inclusive language, replaced by {@link #clusterManagerNodeTimeout}
      */
+    @Deprecated
     public final Request masterNodeTimeout(String timeout) {
         return masterNodeTimeout(TimeValue.parseTimeValue(timeout, null, getClass().getSimpleName() + ".masterNodeTimeout"));
     }
 
+    /**
+     * A timeout value in case the cluster manager has not been discovered yet or disconnected.
+     */
+    public final Request clusterManagerNodeTimeout(String timeout) {
+        return clusterManagerNodeTimeout(TimeValue.parseTimeValue(timeout, null, getClass().getSimpleName() + ".masterNodeTimeout"));
+    }
+
+    /**
+     * @deprecated As of 2.0, because promoting inclusive language, replaced by {@link #clusterManagerNodeTimeout}
+     */
+    @Deprecated
     public final TimeValue masterNodeTimeout() {
         return this.masterNodeTimeout;
     }
+
+    public final TimeValue clusterManagerNodeTimeout() {
+        return this.masterNodeTimeout;
+    }
 }
diff --git a/server/src/main/java/org/opensearch/rest/RestRequest.java b/server/src/main/java/org/opensearch/rest/RestRequest.java
index 7d11da7e122cd..dabcea154ba1d 100644
--- a/server/src/main/java/org/opensearch/rest/RestRequest.java
+++ b/server/src/main/java/org/opensearch/rest/RestRequest.java
@@ -54,6 +54,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
@@ -578,6 +579,31 @@ public static XContentType parseContentType(List<String> header) {
         throw new IllegalArgumentException("empty Content-Type header");
     }
 
+    /**
+     * The method is only used to validate whether the values of the 2 request parameters "master_timeout" and "cluster_manager_timeout" is the same value or not.
+     * If the 2 values are not the same, throw an {@link OpenSearchParseException}.
+     * @param keys Keys of the request parameters.
+     * @deprecated The method will be removed along with the request parameter "master_timeout".
+     */
+    @Deprecated
+    public void validateParamValuesAreEqual(String... keys) {
+        // Filter the non-null values of the parameters with the key, and get the distinct values.
+        Set<String> set = new HashSet<>();
+        for (String key : keys) {
+            String value = param(key);
+            if (value != null) {
+                set.add(value);
+            }
+        }
+        // If there are more than 1 distinct value of the request parameters, throw an exception.
+        if (set.size() > 1) {
+            throw new OpenSearchParseException(
+                "The values of the request parameters: {} are required to be equal, otherwise please only assign value to one of the request parameters.",
+                Arrays.toString(keys)
+            );
+        }
+    }
+
     public static class ContentTypeHeaderException extends RuntimeException {
 
         ContentTypeHeaderException(final IllegalArgumentException cause) {
diff --git a/server/src/main/java/org/opensearch/rest/action/cat/RestPluginsAction.java b/server/src/main/java/org/opensearch/rest/action/cat/RestPluginsAction.java
index 79cac0f906c74..5058967bc55dc 100644
--- a/server/src/main/java/org/opensearch/rest/action/cat/RestPluginsAction.java
+++ b/server/src/main/java/org/opensearch/rest/action/cat/RestPluginsAction.java
@@ -76,6 +76,9 @@ public RestChannelConsumer doCatRequest(final RestRequest request, final NodeCli
         clusterStateRequest.clear().nodes(true);
         clusterStateRequest.local(request.paramAsBoolean("local", clusterStateRequest.local()));
         clusterStateRequest.masterNodeTimeout(request.paramAsTime("master_timeout", clusterStateRequest.masterNodeTimeout()));
+        // Add "cluster_manager_timeout" as the alternative to "master_timeout", for promoting inclusive language.
+        request.validateParamValuesAreEqual("master_timeout", "cluster_manager_timeout");
+        clusterStateRequest.masterNodeTimeout(request.paramAsTime("cluster_manager_timeout", clusterStateRequest.masterNodeTimeout()));
 
         return channel -> client.admin().cluster().state(clusterStateRequest, new RestActionListener<ClusterStateResponse>(channel) {
             @Override