Complex URL
From DigitalJargonBuster
Web addresses (URLs) that are long and contain complex numbers and codes that reflect content which is dynamically called from databases or contains access control information. The term has additional meaning in search engine optimisation because these pages are unlikely to be indexed as the search engine might judge the page not to be permanent and not necessarily available to internet users another time.
An example of this would be a shopping website which uses the URL to carry information about the user's shopping cart contents. A search engine might decide, correctly in this instance, that the page's contents will change and not be reproducible so the page will not be listed.