donicity 

Synonym: donor number DN (misnomer)
https://doi.org/10.1351/goldbook.08164
Quantitative experimental measure of the Lewis basicity of a molecule B, expressed as the negative enthalpy of the formation of the 1:1 complex BSbClA5.
Note:
Donicity is often used as a measure of a solvent’s basicity.
Source:
PAC, 2022, 94, 353. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)) on page 406 [Terms] [Paper]