Introducing additional information in order to solve an ill-posed problem or to prevent overfitting, usually taking the form of a penalty for complexity of the
model.
Source:
PAC, 2016, 88, 239. 'Glossary of terms used in computational drug design, part II (IUPAC Recommendations 2015)' on page 255 (https://doi.org/10.1515/pac-2012-1204)