Unify "file-descriptor" to "file descriptor".

Doc/c-api/abstract.rst

@@ -351,7 +351,7 @@ is considered sufficient for this determination.
 
 .. cfunction:: int PyObject_AsFileDescriptor(PyObject *o)
 
-   Derives a file-descriptor from a Python object.  If the object is an integer or
+   Derives a file descriptor from a Python object.  If the object is an integer or
    long integer, its value is returned.  If not, the object's :meth:`fileno` method
    is called if it exists; the method must return an integer or long integer, which
    is returned as the file descriptor value.  Returns ``-1`` on failure.

Doc/library/os.rst

@@ -651,7 +651,7 @@ by file descriptors.
 .. 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.
 
 

Doc/library/pty.rst

@@ -43,6 +43,6 @@ The :mod:`pty` module defines the following functions:
    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.