[ ɪk'stə:n , ɛk- ]
■ noun
1》 US a non-resident doctor or other worker in a hospital.
2》 (in a strictly enclosed order of nuns) a sister who does not live exclusively within the enclosure and goes on outside errands.
Origin
C16 (as an adjective in the sense '~al'): from Fr. ~e or L. ~us , from exter 'outer'.