nontrivial

( adj.)

   Requiring  real thought or significant computing power. Often used as
   an  understated  way  of  saying that a problem is quite difficult or
   impractical,   or   even   entirely   unsolvable  ("Proving  P=NP  is
   nontrivial").  The  preferred  emphatic form is decidedly nontrivial.
   See {trivial}, {uninteresting}, {interesting}.

[glossary]
[Reference(s) to this entry by made by: {trivial}{uninteresting}]