In general, diagnosis (plural diagnoses) has two distinct dictionary definitions. The first definition is "the recognition of a disease or condition by its outward signs and symptoms", while the second definition is "the analysis of the underlying physiological/biochemical cause(s) of a disease or condition".
Diagnosis covers a broad spectrum, or spectra, of testing in some form of analysis; collective reasoning using such tests is called the method of diagnostics, leading then to the results of those tests by ideal (ethics) would then be considered a diagnosis, but not necessarily the correct one.
In medicine, diagnosis or diagnostics is the process of identifying a medical condition or disease by its signs, symptoms, and from the results of various diagnostic procedures. The conclusion reached through this process is called a diagnosis. The term "diagnostic criteria" designates the combination of symptoms which allows the doctor to ascertain the diagnosis of the respective disease.
Typically, someone with abnormal symptoms will consult a physician, who will then obtain a history of the patient's illness and examine him for signs of disease. The physician will formulate a hypothesis of likely diagnoses and in many cases will obtain further testing to confirm or clarify the diagnosis before providing treatment.
Medical tests commonly performed are measuring blood pressure, checking the pulse rate, listening to the heart with a stethoscope, urine tests, fecal tests, saliva tests, blood tests, medical imaging, electrocardiogram, hydrogen breath test and occasionally biopsy.
The word diagnosis is derived from the Greek words dia which means "by", and gnosis which means "knowledge". The verb is diagnose and a person diagnosing could be considered a diagnostician.