Fr.: opalescence critique
The strong → scattering that occurs in a fluid near the → critical point. Large density fluctuations bring about inhomogeneities of all sizes. This results in the scattering of light at all wavelengths giving a milky appearance to the fluid.
M.E., from M.Fr. opalle, from L. opalus, from Gk. opallios "opal, gem;" probably from a source akin to Skt. upala "jewel, precious stone."
Loan from E., as above.
1) The state of being → opalescent, or
emitting an → iridescence like that of
Exhibiting a play of colors like that of the opal.