"Graphical display", not window system.

lispref/display.texi

@@ -126,7 +126,7 @@ the rightmost column indicates a line that ``wraps'' onto the next line,
 which is also called @dfn{continuing} the line.  (The display table can
 specify alternative indicators; see @ref{Display Tables}.)
 
-  On a window system display, the @samp{$} and @samp{\} indicators are
+  On a graphical display, the @samp{$} and @samp{\} indicators are
 replaced with arrow images displayed in the window fringes
 (@pxref{Fringes}).
 
@@ -1651,13 +1651,13 @@ parts of Emacs text.
 However, if the variable @code{default-line-spacing} is
 non-@code{nil}, it overrides the frame's @code{line-spacing}
 parameter.  An integer value specifies the number of pixels put below
-lines on window systems.  A floating point number specifies the
+lines on graphical displays.  A floating point number specifies the
 spacing relative to the frame's default line height.
 
 @vindex line-spacing
   You can specify the line spacing for all lines in a buffer via the
 buffer-local @code{line-spacing} variable.  An integer value specifies
-the number of pixels put below lines on window systems.  A floating
+the number of pixels put below lines on graphical displays.  A floating
 point number specifies the spacing relative to the default frame line
 height.  This overrides line spacings specified for the frame.
 
@@ -4603,9 +4603,9 @@ command @code{tab-to-tab-stop}.  @xref{Indent Tabs}.
 @tindex indicate-empty-lines
 @cindex fringes, and empty line indication
 When this is non-@code{nil}, Emacs displays a special glyph in the
-fringe of each empty line at the end of the buffer, on terminals that
-support it (window systems).  @xref{Fringes}.
-This variable is automatically buffer-local in every buffer.
+fringe of each empty line at the end of the buffer, on graphical
+displays.  @xref{Fringes}.  This variable is automatically
+buffer-local in every buffer.
 @end defopt
 
 @defvar indicate-buffer-boundaries
@@ -4854,7 +4854,7 @@ on character terminals.  On graphical displays, all glyphs are simple.
 @item @var{string}
 Send the characters in @var{string} to the terminal to output
 this glyph.  This alternative is available on character terminals,
-but not under a window system.
+but not on graphical displays.
 
 @item @var{integer}
 Define this glyph code as an alias for glyph code @var{integer}.  You
@@ -4896,7 +4896,7 @@ This is a synonym for @code{ding}.
 @defopt visible-bell
 This variable determines whether Emacs should flash the screen to
 represent a bell.  Non-@code{nil} means yes, @code{nil} means no.  This
-is effective on a window system, and on a character-only terminal
+is effective on graphical displays, and on text-only terminals
 provided the terminal's Termcap entry defines the visible bell
 capability (@samp{vb}).
 @end defopt

man/killing.texi

@@ -125,7 +125,7 @@ character backwards.
 should be.
 
   Why do we say ``or it should be''?  When Emacs starts up using a
-window system, it determines automatically which key or keys should be
+graphical display, it determines automatically which key or keys should be
 equivalent to @key{DEL}.  As a result, @key{BACKSPACE} and/or @key{DELETE}
 keys normally do the right things.  But in some unusual cases Emacs
 gets the wrong information from the system.  If these keys don't do
@@ -264,7 +264,7 @@ them into Emacs.
 @cindex Delete Selection mode
 @cindex mode, Delete Selection
 @findex delete-selection-mode
-  Many window systems follow the convention that insertion while text
+  Many graphical applications follow the convention that insertion while text
 is selected deletes the selected text.  You can make Emacs behave this
 way by enabling Delete Selection mode---with @kbd{M-x
 delete-selection-mode} or using Custom.  Another effect of this mode