Perhaps the most famous individual to exhibit hypermnesia was a Russian man known as "S," whose amazing photographic memory was studied for 30 years by a psychologist in the early part of the 20th century. Hypermnesia sometimes refers to cases like that of "S," but it can also refer to specific instances of heightened memory (such as those brought on by trauma or hypnosis) experienced by people whose memory abilities are unremarkable under ordinary circumstances. The word hypermnesia, which has been with us since about the mid-19th century, was created in New Latin as the combination of hyper- (meaning "beyond" or "super") and -mnesia (patterned after amnesia). It ultimately derives from the Greek word mnasthai, meaning "to remember."

"Imagine being able to recall anything you've ever dreamt, tasted or read. That's the reality for a woman with a rare condition which means she can remember virtually every single detail of her life—even being able to recite all the Harry Potter books word-for-word. Rebecca Sharrock is one of just 80 people worldwide who have been identified as having … hypermnesia."

— Erin Cardiff, The Mirror, 6 Oct. 2015

 

"'Qui perd gagne!'…, which is translated as 'Loser Take All,' maintains its interest all the way through and awards the viewer with a nice little twist at the end.… Loriot has hypermnesia…. He remembers with total recall absolutely everything he has ever seen or heard, which could drive him crazy without the medication he must take."

— Daniel Neman, The Richmond (Virginia) Times-Dispatch, 2 Apr. 2005

What descendant of mnasthai begins with "a" and refers to the granting of pardon (as by a government) to a large number of persons?