Lewis adduct

https://doi.org/10.1351/goldbook.L03510
The adduct formed between a Lewis acid and a Lewis base.
Source:
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1135 (https://doi.org/10.1351/pac199466051077)