I. -ˈnäs-tik adjective
also di·ag·nos·ti·cal -ti-kəl
Date: 1625
1.
a. : of, relating to, or used in diagnosis
a diagnostic tool
b. : using the methods of or yielding a diagnosis
diagnostic tests
2. : serving to distinguish or identify
a diagnostic feature
• di·ag·nos·ti·cal·ly -ti-k(ə-)lē adverb
II. noun
Date: 1625
1. : the art or practice of diagnosis — often used in plural
2. : a distinguishing mark
• di·ag·nos·ti·cian -(ˌ)näs-ˈti-shən noun