unexplained

from WordNet (r) 3.0 (2006)

unexplained
    adj 1: not explained; "accomplished by some unexplained process"
    2: having the reason or cause not made clear; "an unexplained
       error"

from The Collaborative International Dictionary of English v.0.48

Unexplained \Unexplained\
   See {explained}.

from Moby Thesaurus II by Grady Ward, 1.0

41 Moby Thesaurus words for "unexplained":
      able, enigmatic, incalculable, incognizable, invisible, mysterious,
      puzzling, sealed, strange, unapparent, unapprehended,
      unascertained, unbeknown, uncharted, unclassified, undetected,
      undisclosed, undiscoverable, undiscovered, undivulged, unexplored,
      unexposed, unfamiliar, unfathomed, unheard, unheard-of,
      unidentified, uninvestigated, unknowable, unknown, unperceived,
      unplumbed, unrevealed, unseen, unsolved, unspied, unsuspected,
      untouched, untraced, untracked, virgin