diff --git a/public_html/wp-content/plugins/pattern-directory/includes/pattern-validation.php b/public_html/wp-content/plugins/pattern-directory/includes/pattern-validation.php
index 20a7c345..a0ab4f7f 100644
--- a/public_html/wp-content/plugins/pattern-directory/includes/pattern-validation.php
+++ b/public_html/wp-content/plugins/pattern-directory/includes/pattern-validation.php
@@ -687,10 +687,11 @@ function validate_title( $prepared_post, $request ) {
 		);
 	}
 
-	if ( ! is_title_valid( $title ) ) {
+	$title_error = get_title_error( $title );
+	if ( $title_error ) {
 		return new \WP_Error(
 			'rest_pattern_invalid_title',
-			__( 'Pattern title is invalid. The pattern title should describe the pattern.', 'wporg-patterns' ),
+			$title_error,
 			array( 'status' => 400 )
 		);
 	}
@@ -1120,33 +1121,33 @@ function check_for_spam( $post ) {
 }
 
 /**
- * Helper function to check for a valid pattern title.
+ * Explain why a pattern title is invalid, so the author knows what to change.
  *
  * @param string $title Pattern title.
- * @return boolean
+ * @return string The reason the title is invalid, or an empty string if it's valid.
  */
-function is_title_valid( $title ) {
+function get_title_error( $title ) {
 	if ( strip_shortcodes( $title ) !== $title || wp_strip_all_tags( $title ) !== $title ) {
-		return false;
+		return __( 'Pattern titles cannot contain HTML or shortcodes.', 'wporg-patterns' );
 	}
 
 	if ( content_has_block_directives( $title ) ) {
-		return false;
+		return __( 'Pattern titles cannot contain interactivity directives.', 'wporg-patterns' );
 	}
 
-	// Check title against a list of disallowed words.
-	// Note the space after `test ` to avoid matching "testimonial".
-	$disallow_list = array( 'test ', 'testing', 'my pattern', 'wordpress', 'example' );
-
-	if ( 'test' === strtolower( $title ) ) {
-		return false;
-	}
+	// Whole words only, so "Latest Posts" and "Testimonial" are fine.
+	$disallow_list = array( 'test', 'testing', 'my pattern', 'my patterns', 'wordpress', 'example' );
 
 	foreach ( $disallow_list as $disallowed ) {
-		if ( false !== stripos( $title, $disallowed ) ) {
-			return false;
+		$pattern = '/\b' . str_replace( ' ', '\s+', preg_quote( $disallowed, '/' ) ) . '\b/iu';
+		if ( preg_match( $pattern, $title, $matches ) ) {
+			return sprintf(
+				/* translators: %s: The word from the title that isn't allowed, e.g. "test". */
+				__( 'Pattern titles cannot include "%s". The title should describe the pattern.', 'wporg-patterns' ),
+				$matches[0]
+			);
 		}
 	}
 
-	return true;
+	return '';
 }
diff --git a/public_html/wp-content/plugins/pattern-directory/tests/phpunit/pattern-title-validation-test.php b/public_html/wp-content/plugins/pattern-directory/tests/phpunit/pattern-title-validation-test.php
index d1095243..94fbc860 100644
--- a/public_html/wp-content/plugins/pattern-directory/tests/phpunit/pattern-title-validation-test.php
+++ b/public_html/wp-content/plugins/pattern-directory/tests/phpunit/pattern-title-validation-test.php
@@ -84,6 +84,16 @@ public function data_valid_title() {
 			array(
 				array_merge( $defaults, array( 'title' => 'Testimonial' ) ),
 			),
+			// Disallowed words inside other words.
+			array(
+				array_merge( $defaults, array( 'title' => 'Latest Posts' ) ),
+			),
+			array(
+				array_merge( $defaults, array( 'title' => 'Contest Banner' ) ),
+			),
+			array(
+				array_merge( $defaults, array( 'title' => 'Examples Grid' ) ),
+			),
 			array(
 				array(
 					'title'   => '',
@@ -178,6 +188,49 @@ public function data_invalid_title() {
 		);
 	}
 
+	/**
+	 * Test that the error says why the title is invalid.
+	 *
+	 * @dataProvider data_invalid_title_message
+	 *
+	 * @param string $title            Submitted title.
+	 * @param string $expected_message Expected error message.
+	 */
+	public function test_invalid_title_message( $title, $expected_message ) {
+		wp_set_current_user( self::$user );
+
+		$request = new WP_REST_Request( 'POST', '/wp/v2/wporg-pattern/' . self::$pattern_id );
+		$request->set_header( 'content-type', 'application/json' );
+		$request->set_body(
+			wp_json_encode(
+				array(
+					'title'   => $title,
+					'status'  => 'publish',
+					'content' => self::$valid_content,
+				)
+			)
+		);
+
+		$data = rest_do_request( $request )->get_data();
+		$this->assertSame( 'rest_pattern_invalid_title', $data['code'] );
+		$this->assertSame( $expected_message, $data['message'] );
+	}
+
+	/**
+	 * Data provider for the invalid title messages.
+	 *
+	 * @return array
+	 */
+	public function data_invalid_title_message() {
+		return array(
+			array( 'Test Pattern', 'Pattern titles cannot include "Test". The title should describe the pattern.' ),
+			array( 'My  Pattern', 'Pattern titles cannot include "My  Pattern". The title should describe the pattern.' ),
+			array( 'My Patterns', 'Pattern titles cannot include "My Patterns". The title should describe the pattern.' ),
+			array( 'WordPress Header', 'Pattern titles cannot include "WordPress". The title should describe the pattern.' ),
+			array( 'Quote <span>markup</span>', 'Pattern titles cannot contain HTML or shortcodes.' ),
+		);
+	}
+
 	/**
 	 * Test invalid pattern title: Published pattern, has empty title with no new title.
 	 */