Solvent with a sizable permanent dipole moment that bears suitably acidic hydrogen atoms to form strong intermolecular solvent-solute hydrogen bonds.
Note:
A solvent that is not capable of acting as hydrogen-bond donor is called a non-HBD solvent (formerly aprotic solvent).
Source:
PAC, 2022, 94, 353. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)' on page 430 (https://doi.org/10.1515/pac-2018-1010)