frictionless

from WordNet (r) 3.0 (2006)

frictionless
    adj 1: lacking all friction; "a perpetual motion machine would
           have to be frictionless"

from The Collaborative International Dictionary of English v.0.48

Frictionless \Fric"tion*less\, a.
   Having no friction.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

31 Moby Thesaurus words for "frictionless":
      accordant, agreeable, agreeing, akin, amicable, at one, attuned,
      compatible, concordant, congenial, corresponding, easy-flowing,
      easy-running, empathetic, empathic, en rapport, harmonious,
      in accord, in concert, in rapport, in tune, inharmony, like-minded,
      of one mind, peaceful, smooth-running, sympathetic, together,
      understanding, united, well-oiled