Full Idea
It is normally claimed that Tarski defined truth using no undefined semantic terms, but I argue that he reduced the notion of truth to certain other semantic notions, but did not in any way explicate these other notions.
Gist of Idea
Tarski just reduced truth to some other undefined semantic notions
Source
Hartry Field (Tarski's Theory of Truth [1972], §0)
Book Reference
'The Nature of Truth', ed/tr. Lynch, Michael P. [MIT 2001], p.365