- noting or pertaining to a system of crystallization characterized by three unequal axes intersecting at right angles; rhombic; trimetric.
- crystallog relating to the crystal system characterized by three mutually perpendicular unequal axesAlso: rhombic, trimetric
- Relating to a crystal having three axes of different lengths intersecting at right angles. The mineral topaz has orthorhombic crystals. See illustration at crystal.