A piece of state information supplied by a Web server to a browser, in a response for a requested resource, for the browser to store temporarily and return to the server on any subsequent visits or requests.
Source(s):
CNSSI 4009-2015 from NIST SP 800-28
NIST SP 800-28 Version 2 under Cookie

  A small file that stores information for a Web site.
Source(s):
NIST SP 800-69 [Withdrawn] under Cookie

  A small file that stores information for a Web site on a user’s computer.
Source(s):
NIST SP 800-114 [Superseded] under Cookie

  A character string, placed in a web browser’s memory, which is available to websites within the same Internet domain as the server that placed them in the web browser. Cookies are used for many purposes and may be assertions or may contain pointers to assertions. See Section 9.1.1 for more information.
Source(s):
NIST SP 800-63-2 [Superseded] under Cookie