diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/nested-select-crash.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/nested-select-crash.html
index dc32b95281002..2973b3d6cd32c 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/nested-select-crash.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/nested-select-crash.html
@@ -74,7 +74,7 @@
 ?
 ?
 <
-selectedoption
+selectedcontent
 /
 >
 <
@@ -104,7 +104,7 @@
 ?
 ?
 <
-selectedoption
+selectedcontent
 /
 >
 <
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/resources/selectedoption-restore-iframe.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/resources/selectedcontent-restore-iframe.html
similarity index 91%
rename from testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/resources/selectedoption-restore-iframe.html
rename to testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/resources/selectedcontent-restore-iframe.html
index 03913f7b4b2a3..598f557ce21f6 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/resources/selectedoption-restore-iframe.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/resources/selectedcontent-restore-iframe.html
@@ -42,11 +42,11 @@
 button
 >
 <
-selectedoption
+selectedcontent
 >
 <
 /
-selectedoption
+selectedcontent
 >
 <
 /
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption-in-option-crash.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent-in-option-crash.html
similarity index 85%
rename from testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption-in-option-crash.html
rename to testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent-in-option-crash.html
index 6d3acca27d278..b697b7722787e 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption-in-option-crash.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent-in-option-crash.html
@@ -75,11 +75,11 @@
 button
 >
 <
-selectedoption
+selectedcontent
 >
 <
 /
-selectedoption
+selectedcontent
 >
 <
 /
@@ -90,11 +90,11 @@
 >
 one
 <
-selectedoption
+selectedcontent
 >
 <
 /
-selectedoption
+selectedcontent
 >
 <
 /
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption-restore.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent-restore.tentative.html
similarity index 96%
rename from testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption-restore.tentative.html
rename to testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent-restore.tentative.html
index 39df31b250fbe..798e17308756f 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption-restore.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent-restore.tentative.html
@@ -121,7 +121,7 @@
 "
 resources
 /
-selectedoption
+selectedcontent
 -
 restore
 -
@@ -339,7 +339,7 @@
 querySelector
 (
 '
-selectedoption
+selectedcontent
 '
 )
 .
@@ -362,7 +362,7 @@
 .
 innerHTML
 '
-selectedoption
+selectedcontent
 .
 innerHTML
 should
@@ -378,7 +378,7 @@
 }
 '
 <
-selectedoption
+selectedcontent
 >
 should
 be
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent.tentative.html
similarity index 88%
rename from testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption.tentative.html
rename to testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent.tentative.html
index 5f67495464296..310c494a25590 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoption.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontent.tentative.html
@@ -147,11 +147,11 @@
 button
 >
 <
-selectedoption
+selectedcontent
 >
 <
 /
-selectedoption
+selectedcontent
 >
 <
 /
@@ -255,14 +255,14 @@
 )
 ;
 const
-selectedOption
+selectedcontent
 =
 document
 .
 querySelector
 (
 '
-selectedoption
+selectedcontent
 '
 )
 ;
@@ -318,7 +318,7 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 optionOne
@@ -329,7 +329,7 @@
 innerHTML
 of
 <
-selectedoption
+selectedcontent
 >
 should
 initially
@@ -363,7 +363,7 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 optionTwo
@@ -374,7 +374,7 @@
 innerHTML
 of
 <
-selectedoption
+selectedcontent
 >
 should
 change
@@ -413,13 +413,13 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 oldInnerHTML
 '
 <
-selectedoption
+selectedcontent
 >
 should
 not
@@ -458,13 +458,13 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 oldInnerHTML
 '
 <
-selectedoption
+selectedcontent
 >
 should
 not
@@ -507,13 +507,13 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 oldInnerHTML
 '
 <
-selectedoption
+selectedcontent
 >
 should
 not
@@ -572,7 +572,7 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 optionOne
@@ -583,7 +583,7 @@
 innerHTML
 of
 <
-selectedoption
+selectedcontent
 >
 should
 be
@@ -650,7 +650,7 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 optionTwo
@@ -666,13 +666,13 @@
 update
 the
 <
-selectedoption
+selectedcontent
 >
 .
 '
 )
 ;
-selectedOption
+selectedcontent
 .
 remove
 (
@@ -687,7 +687,7 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 '
@@ -696,7 +696,7 @@
 Removing
 the
 <
-selectedoption
+selectedcontent
 >
 from
 the
@@ -717,12 +717,12 @@
 .
 appendChild
 (
-selectedOption
+selectedcontent
 )
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 optionTwo
@@ -734,7 +734,7 @@
 inserting
 the
 <
-selectedoption
+selectedcontent
 >
 should
 make
@@ -761,7 +761,7 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 optionOne
@@ -772,7 +772,7 @@
 innerHTML
 of
 <
-selectedoption
+selectedcontent
 >
 should
 be
@@ -797,7 +797,7 @@
 ;
 assert_equals
 (
-selectedOption
+selectedcontent
 .
 innerHTML
 '
@@ -807,7 +807,7 @@
 content
 of
 <
-selectedoption
+selectedcontent
 >
 should
 be
@@ -846,7 +846,7 @@
 '
 The
 <
-selectedoption
+selectedcontent
 >
 element
 should
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoptionelement-attr.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontentelement-attr.tentative.html
similarity index 77%
rename from testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoptionelement-attr.tentative.html
rename to testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontentelement-attr.tentative.html
index f99ec2f60345b..c18f2da067b8c 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedoptionelement-attr.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/selectedcontentelement-attr.tentative.html
@@ -141,14 +141,14 @@
 select
 >
 <
-selectedoption
+selectedcontent
 id
 =
-myselectedoption
+myselectedcontent
 >
 <
 /
-selectedoption
+selectedcontent
 >
 <
 script
@@ -174,14 +174,14 @@
 )
 ;
 const
-selectedoption
+selectedcontent
 =
 document
 .
 querySelector
 (
 '
-selectedoption
+selectedcontent
 '
 )
 ;
@@ -218,16 +218,16 @@
 setAttribute
 (
 '
-selectedoptionelement
+selectedcontentelement
 '
 '
-myselectedoption
+myselectedcontent
 '
 )
 ;
 assert_equals
 (
-selectedoption
+selectedcontent
 .
 innerHTML
 optionOne
@@ -236,7 +236,7 @@
 '
 Setting
 the
-selectedoptionelement
+selectedcontentelement
 attribute
 via
 setAttribute
@@ -247,7 +247,7 @@
 contents
 of
 <
-selectedoption
+selectedcontent
 >
 .
 '
@@ -258,13 +258,13 @@
 removeAttribute
 (
 '
-selectedoptionelement
+selectedcontentelement
 '
 )
 ;
 assert_equals
 (
-selectedoption
+selectedcontent
 .
 innerHTML
 '
@@ -272,7 +272,7 @@
 '
 Removing
 the
-selectedoptionelement
+selectedcontentelement
 attribute
 via
 removeAttribute
@@ -284,7 +284,7 @@
 of
 the
 <
-selectedoption
+selectedcontent
 >
 .
 '
@@ -292,13 +292,13 @@
 ;
 select
 .
-selectedOptionElement
+selectedContentElement
 =
-selectedoption
+selectedcontent
 ;
 assert_equals
 (
-selectedoption
+selectedcontent
 .
 innerHTML
 optionOne
@@ -307,7 +307,7 @@
 '
 Setting
 the
-selectedoptionelement
+selectedcontentelement
 attribute
 via
 IDL
@@ -318,7 +318,7 @@
 contents
 of
 <
-selectedoption
+selectedcontent
 >
 .
 '
@@ -326,13 +326,13 @@
 ;
 select
 .
-selectedOptionElement
+selectedContentElement
 =
 null
 ;
 assert_equals
 (
-selectedoption
+selectedcontent
 .
 innerHTML
 '
@@ -340,7 +340,7 @@
 '
 Removing
 the
-selectedoptionelement
+selectedcontentelement
 attribute
 via
 IDL
@@ -352,7 +352,7 @@
 of
 the
 <
-selectedoption
+selectedcontent
 >
 .
 '
@@ -360,13 +360,13 @@
 ;
 select
 .
-selectedOptionElement
+selectedContentElement
 =
-selectedoption
+selectedcontent
 ;
 assert_equals
 (
-selectedoption
+selectedcontent
 .
 innerHTML
 optionOne
@@ -377,7 +377,7 @@
 -
 setting
 the
-selectedoptionelement
+selectedcontentelement
 attribute
 via
 IDL
@@ -388,7 +388,7 @@
 contents
 of
 <
-selectedoption
+selectedcontent
 >
 .
 '
@@ -423,7 +423,7 @@
 ;
 assert_equals
 (
-selectedoption
+selectedcontent
 .
 innerHTML
 oldInnerHTML
@@ -439,7 +439,7 @@
 update
 the
 <
-selectedoption
+selectedcontent
 >
 contents
 .
@@ -456,7 +456,7 @@
 ;
 assert_equals
 (
-selectedoption
+selectedcontent
 .
 innerHTML
 optionTwo
@@ -475,7 +475,7 @@
 update
 the
 <
-selectedoption
+selectedcontent
 >
 contents
 .
@@ -485,7 +485,7 @@
 }
 '
 The
-selectedoptionelement
+selectedcontentelement
 attribute
 should
 set
@@ -497,7 +497,7 @@
 select
 and
 a
-selectedoption
+selectedcontent
 .
 '
 )
diff --git a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/switch-picker-appearance.tentative.html b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/switch-picker-appearance.tentative.html
index 429542db01782..720085d4e2ef2 100644
--- a/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/switch-picker-appearance.tentative.html
+++ b/testing/web-platform/tests/html/semantics/forms/the-select-element/customizable-select/switch-picker-appearance.tentative.html
@@ -1553,11 +1553,11 @@
 button
 >
 <
-selectedoption
+selectedcontent
 >
 <
 /
-selectedoption
+selectedcontent
 >
 <
 /