diff --git a/platform/util/src/com/intellij/openapi/util/text/Pluralizer.java b/platform/util/src/com/intellij/openapi/util/text/Pluralizer.java
index adb247078af2..30a9e1bf3866 100644
--- a/platform/util/src/com/intellij/openapi/util/text/Pluralizer.java
+++ b/platform/util/src/com/intellij/openapi/util/text/Pluralizer.java
@@ -30,6 +30,7 @@ import com.intellij.util.Consumer;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.containers.JBIterable;
 import com.intellij.util.text.CaseInsensitiveStringHashingStrategy;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.List;
 import java.util.Map;
@@ -37,6 +38,8 @@ import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import static com.intellij.openapi.util.text.StringUtil.notNullize;
+
 /**
  * A java version of http://github.com/blakeembrey/pluralize
  * Revision: 90d82f88428f057c4b7a1d46aa38fc7c44d2d869
@@ -98,11 +101,12 @@ class Pluralizer {
         return matcher.replaceFirst(rule.second);
       }
     }
-    return word;
+    return null;
   }
 
   /**
    * Replace a word with the updated word.
+   * @return null if no applicable rules found
    */
   private String replaceWord(String word, Map<String, String> replaceMap, Map<String, String> keepMap, List<Pair<Pattern, String>> rules) {
     if (StringUtil.isEmpty(word)) return word;
@@ -112,8 +116,9 @@ class Pluralizer {
     if (keepMap.containsKey(word)) return word;
 
     // Check against the replacement map for a direct word replacement.
-    if (replaceMap.containsKey(word)) {
-      return restoreCase(word, replaceMap.get(word));
+    String replacement = replaceMap.get(word);
+    if (replacement != null) {
+      return replacement;
     }
 
     // Run all the rules against the word.
@@ -126,14 +131,16 @@ class Pluralizer {
   public String pluralize(String word, int count, boolean inclusive) {
     String pluralized = count == 1 ? singular(word) : plural(word);
 
-    return (inclusive ? count + " " : "") + pluralized;
+    return (inclusive ? count + " " : "") + notNullize(pluralized, word);
   }
 
-  public String plural(String word) {
+  @Nullable
+  public String plural(@Nullable String word) {
     return restoreCase(word, replaceWord(word, irregularSingles, irregularPlurals, pluralRules));
   }
 
-  public String singular(String word) {
+  @Nullable
+  public String singular(@Nullable String word) {
     return restoreCase(word, replaceWord(word, irregularPlurals, irregularSingles, singularRules));
   }
 
@@ -258,7 +265,6 @@ class Pluralizer {
       {"/(child)(?:ren)?$", "$1ren"},
       {"/eaux$", "$0"},
       {"/m[ae]n$", "men"},
-      {"thou", "you"}
     }).consumeEach(new Consumer<String[]>() {
       @Override
       public void consume(String[] o) {
@@ -271,7 +277,7 @@ class Pluralizer {
      */
     JBIterable.of(new String[][]{
       {"/(.)s$", "$1"},
-      {"/(ss)$", "$1"},
+      {"/([^aeiou]s)es$", "$1"},
       {"/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)(?:sis|ses)$", "$1sis"},
       {"/(^analy)(?:sis|ses)$", "$1sis"},
       {"/(wi|kni|(?:after|half|high|low|mid|non|night|[^\\w]|^)li)ves$", "$1fe"},
@@ -281,7 +287,7 @@ class Pluralizer {
       {"/\\b(mon|smil)ies$", "$1ey"},
       {"/(m|l)ice$", "$1ouse"},
       {"/(seraph|cherub)im$", "$1"},
-      {"/(x|ch|ss|sh|zz|tto|go|cho|alias|[^aou]us|tlas|gas|(?:her|at|gr)o|ris)(?:es)?$", "$1"},
+      {"/(x|ch|.ss|sh|zz|tto|go|cho|alias|[^aou]us|tlas|gas|(?:her|at|gr)o|ris)(?:es)?$", "$1"},
       {"/(e[mn]u)s?$", "$1"},
       {"/(cookie|movie|twelve)s$", "$1"},
       {"/(cris|test|diagnos)(?:is|es)$", "$1is"},
diff --git a/platform/util/src/com/intellij/openapi/util/text/StringUtil.java b/platform/util/src/com/intellij/openapi/util/text/StringUtil.java
index 80de7a697048..518a150bd21a 100644
--- a/platform/util/src/com/intellij/openapi/util/text/StringUtil.java
+++ b/platform/util/src/com/intellij/openapi/util/text/StringUtil.java
@@ -830,8 +830,9 @@ public class StringUtil extends StringUtilRt {
   @Contract(pure = true)
   public static String pluralize(@NotNull String word) {
     String plural = Pluralizer.PLURALIZER.plural(word);
-    return equalsIgnoreCase(plural, word) && !endsWithIgnoreCase(plural, "es") ?
-           Pluralizer.restoreCase(word, word + "s") : plural;
+    if (plural != null) return plural;
+    if (word.endsWith("s")) return Pluralizer.restoreCase(word, word + "es");
+    return Pluralizer.restoreCase(word, word + "s");
   }
 
   @NotNull
@@ -1647,10 +1648,10 @@ public class StringUtil extends StringUtilRt {
   @Contract(pure = true)
   public static String unpluralize(@NotNull String word) {
     String singular = Pluralizer.PLURALIZER.singular(word);
-    if (equalsIgnoreCase(singular, word)) {
-      singular = nullize(trimEnd(singular, "s", true));
-    }
-    return equalsIgnoreCase(singular, word) ? null : singular;
+    if (singular != null) return singular;
+    if (word.endsWith("es")) return nullize(trimEnd(word, "es", true));
+    if (word.endsWith("s")) return nullize(trimEnd(word, "s", true));
+    return null;
   }
 
   @Contract(pure = true)
diff --git a/platform/util/testSrc/com/intellij/util/text/StringUtilTest.java b/platform/util/testSrc/com/intellij/util/text/StringUtilTest.java
index e4d7f69bf81e..68020f91fe89 100644
--- a/platform/util/testSrc/com/intellij/util/text/StringUtilTest.java
+++ b/platform/util/testSrc/com/intellij/util/text/StringUtilTest.java
@@ -98,16 +98,22 @@ public class StringUtilTest {
 
   @Test
   public void testUnPluralize() {
-    assertEquals("plurals", StringUtil.unpluralize("pluralss"));
+    // synthetic
+    assertEquals("plurals", StringUtil.unpluralize("pluralses"));
+    assertEquals("Inherits", StringUtil.unpluralize("Inheritses"));
+    assertEquals("s", StringUtil.unpluralize("ss"));
     assertEquals("I", StringUtil.unpluralize("Is"));
     assertEquals(null, StringUtil.unpluralize("s"));
     assertEquals("z", StringUtil.unpluralize("zs"));
+    // normal
+    assertEquals("case", StringUtil.unpluralize("cases"));
     assertEquals("Index", StringUtil.unpluralize("Indices"));
     assertEquals("fix", StringUtil.unpluralize("fixes"));
     assertEquals("man", StringUtil.unpluralize("men"));
     assertEquals("leaf", StringUtil.unpluralize("leaves"));
     assertEquals("cookie", StringUtil.unpluralize("cookies"));
     assertEquals("search", StringUtil.unpluralize("searches"));
+    assertEquals("process", StringUtil.unpluralize("process"));
   }
 
   @Test