mass ratio

symbol: $\zeta$
https://doi.org/10.1351/goldbook.15337
Mass of one constituent \(\ce{A}\) divided by the mass of a second constituent \(\ce{B}\) in the same system. \[\zeta_{\ce{A,B}} = m_{\ce{A}}/m_{\ce{B}}\]
Source:
PAC, 2008, 80, 233. (Glossary of terms related to solubility (IUPAC Recommendations 2008)) on page 253 [Terms] [Paper]