I'm referring to the "evil demon", "malicious demon", "evil genius", etc, depending on translation. I'm looking for the original latin phrase.
From meditation 1:
, sed genium aliquem malignum eundemque summe potentem et callidum omnem suam industriam in eo posuisse, ut me falleret: (http://www.gutenberg.org/files/23306/23306-h/23306-h.htm)
genium malignum --> evil genius
or possibly genius malignus
depending on how he's doing his declining of Latin.
but some evil genius not less powerful than deceitful, has employed his whole energies in deceiving me (http://selfpace.uconn.edu/class/percep/DescartesMeditations.pdf)