Sample characterized by a (unique) sample axis Z with all directions perpendicular
to Z being equivalent. In other words, the sample properties are invariant
to rotation around Z. Uniaxiality exists in many anisotropic samples and simplifies
the interpretation of their spectra considerably.
Source:
PAC, 2007, 79, 293
(Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006))
on page 437