1 : arising spontaneously or from an obscure or unknown cause
2 : peculiar to the individual
"Some dogs have idiopathic epilepsy, which means there's no real explanation for their seizures, though even a reasonably mild stressor may increase the odds of a seizure." - From an article by Steve Dale in the Orlando (Florida) Sentinel, November 13, 2012
"Juvenile idiopathic arthritis, diagnosed before age 16, causes chronic swelling of the joints along with redness, [Dr. Hilary] Haftel said." - From an article by Amanda Whitesell in the Livingston County (Michigan) Press, January 11, 2013
Did You Know?
"Idiopathic" joins the combining form "idio-" (from Greek "idios," meaning "one's own" or "private") with "-pathic," a form that suggests the effects of disease. The combining form "idio-" is typically found in technical terms. Examples include "idiographic," meaning "relating to or dealing with something concrete, individual, or unique"; "idiolect," meaning "the language or speech pattern of one individual at a particular period of life"; and "idiotype," meaning "the molecular structure and conformation of an antibody that confers its antigenic specificity." A more common "idio-" word is "idiosyncrasy," which most commonly refers to an unusual way in which a person behaves or thinks, or to an unusual part or feature of something.
Word Family Quiz
What member of the "idios" family can refer to an expression that is peculiar to itself either grammatically or in having a meaning that cannot be understood from the meanings of its separate words? The answer is …