a part of a structure having some specific characteristic or function | the crescent-shaped area at the base of the human fingernail |
the extent of a 2-dimensional surface enclosed within a boundary | the time at which the Moon is at first or last quarter when half its face is illuminated |
a part of an animal that has a special function or is supplied by a given artery or nerve | |
a subject of study | |
a particular geographical region of indefinite boundary (usually serving some special purpose or distinguished by its people or culture or geography) | |
a particular environment or walk of life | |