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.
Test Your Vocabulary with M-W Quizzes
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 …