Resuscitation cache
A resuscitation cache, resus cache or lonely cache is a cache that has not received a "found it" log for a significant period of time, usually considered to be at least twelve months. Finding such caches is sometimes considered prestigious, but is not considered an official statistic since it depends on the actions of others. For this reason, they can no longer be used as criteria for challenge caches.
A tool to give the number of resuscitation caches found by a given user can be found here.