acceptor number, \(\text{AN}\)

https://doi.org/10.1351/goldbook.A00056
A quantitative measure of Lewis acidity.
Source:
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1081 (https://doi.org/10.1351/pac199466051077)