penumbra
C1CEFR level
65/100Rarity: rare
TechnicalRegister
General noun
A region of partial shadow; figuratively, a peripheral, indeterminate, or ambiguous area.
The statute leaves a penumbra of cases that neither clearly falls inside nor outside its scope.
Medicine noun
The zone of hypoperfused but still salvageable brain tissue surrounding the irreversibly damaged core of an infarct.
The goal of thrombolysis is to rescue the ischaemic penumbra before it is recruited into the infarct core.
Rarity runs from 0 (a word everyone knows) to 100 (almost never seen outside specialist or literary writing). Level is the word's real difficulty on the CEFR scale, from A1 to C2.
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