You might look at Apte's Eng-Skt dict for some ideas.
But as always with such queries (like last year's 'What's the Sanskrit for "go with the flow"?'), one has first to ask whether there is a Sanskritic concept that might correspond to English "mysticism."   And, most probably, there isn't, quite.  Much interesting work has been done on incommensurability in translation theory.

Dominik




On 29 April 2012 13:49, Harsha Dehejia <harshadehejia@hotmail.com> wrote:
Friends~
 
What is the best Sanskrit word for mysticism?
 
Regards.
 
Harsha
Prof. Harsha V. dehejia
Carleton University, Ottawa, ON., Canada.