Synonym word of unexplained:

X, alien, anonymous, concealed, dark, desolate, distant, exotic, far, far-off, faraway, foreign, hidden, humble, incog, incognito, little known, nameless, new, remote, secret, so-and-so, strange, such-and-such, unapprehended, unascertained, uncelebrated, uncharted, undiscovered, undistinguished, unexplained, unexplored, unfamiliar, unheard-of, unidentified, unnamed, unnoted, unperceived, unrecognized, unrenowned, unrevealed, unsung, untold