https://doi.org/10.1351/goldbook.D01801
  1. The separation of a @M03986@ into two or more molecular entities (or any similar separation within a polyatomic molecular entity). Examples include @M03989@ and @H02851@, and the separation of the constituents of an @I03231@ into free ions.
  2. The separation of the constituents of any aggregate of molecular entities.
In both senses dissociation is the reverse of @A00472@.
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1107 [Terms] [Paper]