Not explained. Of unknown cause or origin.(adjective)
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Use "unexplained" in a sentence
"They don't even know what to call it, opting for the label "unexplained dermopathy" in their paper."
"That's sometimes summarized in what I called the unexplained portion of the pay gap, and that unexplained portion of the pay gap has declined over time; it represents the influence of everything that's difficult to account for in terms of job characteristics, industry mix, characteristics of workers, their experience in the labor force."
"Although Morgellons disease isn't widely recognized as a medical diagnosis, experts from the Centers for Disease Control and Prevention (CDC) are investigating reports of the condition, which they refer to as unexplained dermopathy."