/ek"sterrn/ ; for 3 also /ik sterrn"/ , n.
1. a person connected with an institution but not residing in it, as a doctor or medical student at a hospital.
2. a nun of a strictly enclosed order, as the Carmelites, who resides inside the convent but outside its enclosure and who chiefly goes on outside errands.
adj.
3. Archaic. external; outer.
[ 1525-35; externus, deriv. of exter, exterus. See EXTERIOR ]