Unify "file-descriptor" to "file descriptor".
diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index 24830d2..bc4cf42 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -651,7 +651,7 @@
 .. function:: ttyname(fd)
 
    Return a string which specifies the terminal device associated with
-   file-descriptor *fd*.  If *fd* is not associated with a terminal device, an
+   file descriptor *fd*.  If *fd* is not associated with a terminal device, an
    exception is raised. Availability:Macintosh, Unix.
 
 
diff --git a/Doc/library/pty.rst b/Doc/library/pty.rst
index 5e1da22..ec1c75f 100644
--- a/Doc/library/pty.rst
+++ b/Doc/library/pty.rst
@@ -43,6 +43,6 @@
    reading from the controlling terminal.
 
    The functions *master_read* and *stdin_read* should be functions which read from
-   a file-descriptor. The defaults try to read 1024 bytes each time they are
+   a file descriptor. The defaults try to read 1024 bytes each time they are
    called.