Full Idea
The desired definition of truth does not aim to specify the meaning of a familiar word used to denote a novel notion; on the contrary, it aims to catch hold of the actual meaning of an old notion.
Gist of Idea
Definitions of truth should not introduce a new version of the concept, but capture the old one
Source
Alfred Tarski (The Semantic Conception of Truth [1944], 01)
Book Reference
'Semantics and the Philosophy of Language', ed/tr. Linsky,Leonard [University of Illinois 1972], p.13
A Reaction
Tarski refers back to Aristotle for an account of the 'old notion'. To many the definition of Tarski looks very weird, so it is important to see that he is trying to capture the original concept.