The boundary of a convex set is always a convex curve. The intersection of all convex sets containing a given subset A of Euclidean space is called the convex hull of A. It is the smallest convex set containing A.
Rector (ecclesiastical) A rector is, in an ecclesiastical sense, a cleric who functions as an administrative leader in some Christian denominations, and in Islam. In contrast, a vicar is also a cleric but functions as an assistant and representative of an administrative leader.
Sinecure, properly a term of ecclesiastical law for a benefice without the care of souls, arose in the English Church when the rector had no care of souls nor resided in the parish, the work of the incumbent being performed by a vicar. Such sinecure rectories were expressly granted by the patron.