Source : Webster's Revised Unabridged Dictionary (1913)

Dextral \Dex"tral\, a. [From {Dexter}.]
   Right, as opposed to sinistral, or left.

   {Dextral shell} (Zo["o]l.), a spiral shell the whorls of
      which turn from left right, or like the hands of a watch
      when the apex of the spire is toward the eye of the
      observer.

Source : WordNet®

dextral
     adj 1: of or on the right; "a dextral gastropod shell with the apex
            upward has its opening on the right when facing the
            observer"; "a dextral flatfish lies with the right eye
            uppermost" [ant: {sinistral}]
     2: preferring to use right foot or hand or eye; "dextral
        individuals exhibit dominance of the right hand and eye"