cookie

n. A handle, transaction ID, or other token of agreement between cooperating
programs. I give him a packet, he gives me back a cookie. The claim check
you get from a dry-cleaning shop is a perfect mundane example of a cookie;
the only thing it's useful for is to relate a later transaction to this one
(so you get the same clothes back). Syn. magic cookie ; see also fortune
cookie. Now mainstream in the specific sense of web-browser cookies.

