Full Idea
Explicit definitions allow for a complete elimination of the defined notion (at least in extensional contexts).
Gist of Idea
An explicit definition enables the elimination of what is defined
Source
Volker Halbach (Axiomatic Theories of Truth [2011], 1)
Book Reference
Halbach,Volker: 'Axiomatic Theories of Truth' [CUP 2011], p.3
A Reaction
If the context isn't extensional (concerning the things themselves) then we could define one description of it, but be unable to eliminate it under another description. Elimination is no the aim of an Aristotelian definition. Halbach refers to truth.