characteristic or indicative of e.g. a disease; "a diagnostic sign of yellow fever"; "diagnostic information"; "a rash symptomatic of scarlet fever"; "symptomatic of insanity"; "a rise in crime symptomatic of social breakdown"
concerned with diagnosis; used for furthering diagnosis; "a diagnostic clinic"; "a diagnostic reading test"; "diagnostic information"
a grammatical number category referring to two items or units as opposed to one item (singular) or more than two items (plural); "ancient Greek had the dual form but it has merged with the plural form in modern Greek"