Nescient is from the Latin - ne (not) + scire (know) = nescire.   Latin - Nescient (not knowing) 

The earliest known use of the word nescient is in the Middle English period (1150—1500). OED's earliest evidence for nescient is from before 1500, in Speculum Sacerdotale. nescient is a borrowing from Latin. Etymons: Latin nescient-, nesciēns, nescīre.  
 

nescient - noun (plural nescients)  1. An ignorant person.  2. One who holds that only material phenomena can be known and knowledge of spiritual matters (the unmeasurable) or ultimate causes is impossible.