diagnose

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To distinguish or identify (a disease, for example) by diagnosis.
• intransitive verb To identify (a person) as having a particular disease or condition by means of a diagnosis.
• intransitive verb To analyze the nature or cause of.
• intransitive verb To make a diagnosis.

from The Century Dictionary.

• In pathol., zoöl., and botany, to determine the diagnosis of; ascertain, as a disease, from its symptoms; distinguish; discriminate; diagnosticate.

from the GNU version of the Collaborative International Dictionary of English.

• verb To ascertain by diagnosis; to diagnosticate. See diagnosticate.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb transitive, medicine To determine the root cause of (a disease).

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb determine or distinguish the nature of a problem or an illness through a diagnostic analysis
• verb subject to a medical analysis