well-defined

/W EH1 L D IH0 F AY0 N D/
adjective
  1. 1

    Having a clean and distinct outline

  2. 2

    Accurately and precisely described or specified

  3. 3

    Defined in an unambiguous and consistent way: specifically, such that any two objects implied to be identical are indeed identical.

Antonyms

Source: https://en.wiktionary.org/wiki/well-defined