Full Idea
A definition allows a defined term to be eliminated in every context in which it appears.
Gist of Idea
A definition should allow the defined term to be eliminated
Source
Leon Horsten (The Tarskian Turn [2011], 04.2)
Book Reference
Horsten,Leon: 'The Tarskian Turn' [MIT 2011], p.51
A Reaction
To do that, a definition had better be incredibly comprehensive, so that no nice nuance of the original term is thrown out.