The Free On-line Dictionary of Computing (30 December 2018):

speculative evaluation

    A technique used in parallel processing where
   some evaluation may be started before it is known whether it
   is needed (Eager evaluation).  This may result in some wasted
   processing and may introduce unnecessary non-terminating
   processes but it can reduce the overall run time by making
   some needed results available earlier than they would be
   otherwise.

   Opposite: conservative evaluation.

   (1995-05-05)