gistfile1.el

(defun wordnet (word)
  "Check word definition from WordNet command line program"
  (interactive
   (list (read-string "Check for word: "
                      (apply 'buffer-substring
                             (let (bounds)
                               (if (use-region-p)
                                   (setq bounds (cons (region-beginning) (region-end)))
                                 (setq bounds (bounds-of-thing-at-point 'word)))
                               (list (car bounds) (cdr bounds)))))))
  (with-output-to-temp-buffer "*WordNet*"
    (princ (shell-command-to-string (format "wn %s -over" word)))))

(global-set-key (kbd "C-c w") 'wordnet)