A room is a set of (usually) orthogonally connected cells, usually surrounded by bold lines. In some puzzles the diagramm is divided into rooms (e.g. Heyawake, LITS, Country Road), in other puzzles the division into rooms is the solution of the puzzle (Fillomino, Galaxies, Burokku).Area:
An area is a set of (usually) orthogonally connected cells, not surrounded by bold lines, but defined otherwise. For example, all blackened cells in Nurikabe must form a single area of orthogonally connected cells and the embedded areas of white cells must not be orthogonally adjacent. The black cells must not form an area which includes a square of size 2x2.Room/Area of orthogonally connected cells: Transitive closure
of cells w.r.t. the orthogonally adjacent
Is there a better definition in plain English?