The Collaborative International Dictionary of English v.0.48:
-ist \-ist\ ([i^]sh"[-u]*[i^]st). [Gr. ?: cf. F. -iste.]
   A noun suffix denoting an agent, or doer, one who practices,
   a believer in; as, theorist, one who theorizes; socialist,
   one who holds to socialism; sensualist, one given to
   sensuality.
   [1913 Webster]
The Collaborative International Dictionary of English v.0.48:
Is't \Is't\
   A contraction of is it.
   [1913 Webster]
V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):
IST
       Immerse System Technology (VR)
V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):
IST
       Indian Standard Time [+0530] (TZ)
V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):
IST
       Initial System Test