gistfile1.el

(require 'url)
(require 'json)

(defun ud-define (wd)
  (interactive "M")
  (let ((url-request-method "GET"))
    (url-retrieve (concat "http://urbanscraper.herokuapp.com/define/" wd ".json")
                  (lambda (x)
                    (goto-char (point-min))
                    (search-forward-regexp "\{.*")
                    (setq word-definition (gethash "definition"
                                                   (let ((json-object-type 'hash-table))
                                                     (json-read-from-string (match-string-no-properties 0)))))))
    (message word-definition)))

(ud-define "bazooka")