Of or pertaining to the left side; situated on the left hand; not dextral; sinister; sinistrous.In conchology, reversed from the usual, right, or dextral curve, as the whorls of a spiral shell; whorled toward the left; sinistrorse; heterostrophous.In ichthyology, having both eyes on the left side of the head, as certain flatfishes.Sinister; wrong.