There is a
chemical bond between two atoms or groups of atoms in the case that the forces acting between them
are such as to lead to the formation of an aggregate with sufficient stability to
make it convenient for the chemist to consider it as an independent '
molecular species'.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1089