Diagnostic is an adjective meaning "relating to diagnosis" or "used for diagnosis." It refers to equipment, methods, or systems used for discovering what is wrong with people or things.
[ADJ 形容词](用于)诊断的；(用于)判断的Diagnostic equipment, methods, or systems are used for discovering what is wrong with people who are ill or with things that do not work properly.
[ADJ n]
...X-rays and other diagnostic tools.
X射线和其他诊断工具
Oxford
diag·nos·tic/ˌdaɪəɡˈnɒstɪk; NAmEˌdaɪəɡˈnɑːstɪk/
adjective
,
noun
diagnosticdiagnosticsadjective[usually before noun ]( technical 术语) connected with identifying sth, especially an illness 诊断的；判断的◆to carry out diagnostic assessments/tests进行诊断性评估╱化验◆specific conditions which are diagnostic of AIDS诊断为艾滋病的具体症状noun( computing 计) 1(alsoˌdiagˈnostic program)[countable ]a program used for identifying a computer fault 诊断程序， 诊断程式（诊断计算机的错误） 2[countable ]a message on a computer screen giving information about a fault 诊断提示（计算机错误的显示）3diagnostics[uncountable ]the practice or methods of diagnosis诊断；诊断法diag·nos·tic/ˌdaɪəɡˈnɒstɪk; NAmEˌdaɪəɡˈnɑːstɪk/