microscope

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. An optical instrument that uses a lens or a combination of lenses to produce magnified images of small objects, especially of objects too small to be seen by the unaided eye.
2. n. An instrument, such as an electron microscope, that uses electronic or other processes to magnify objects.

Century Dictionary and Cyclopedia

1. n. An optical instrument consisting of a lens or combination of lenses (in some cases mirrors also) which magnifies and thus renders visible minute objects that cannot be seen by the naked eye, or enlarges the apparent magnitude of small visible bodies, so as to render possible the examination of their texture or structure. The single microscope, which is the simplest form, is merely a convex lens, near to which the object to be examined is placed; it is also called a magnifying-glass or -lens (see magnifying-lens, under lens). The compound microscope consists essentially of two lenses, or systems of lenses, one of which, the object-glass or objective, forms an enlarged inverted image of the object, and the other, the eyepiece or ocular, magnifies this image. The eyepiece and objective (see these words) are placed at the opposite ends of the tube or body, which is often made of two closely fitting parts so that its length (and thus the distance between the glasses) can be varied at will; it is then called a draw-tube. The object under examination is placed upon a support, called the stage, beneath the objective; its position upon this may be adjusted by the hand, or, better, the object and the stage (then called a mechanical stage) are moved together by some mechanical arrangement, as, for example, by two screws giving motions in two directions at right angles. The proper distance between the objective and the object (such that the image of the latter shall be seen clearly, or be in focus) is usually attained by the movement of the tube as a whole. This is accomplished by the rapid motion of the coarse adjustment, and more slowly and accurately, as is necessary in the case of high powers, by an arrangement called the slow motion or fine adjustment. The necessary illumination is obtained by a concave mirror below the stage, which reflects the light upon the object. An achromatic condenser, usually in connection with a diaphragm, is often added to converge the light more strongly; for opaque objects a bull's-eye condenser, a lieberkuhn, or some other form of reflector is employed. The body of the microscope, with the stage, etc., is supported firmly upon a stand, and usually attached by a joint which allows of its being inclined at any desired angle between the vertical and horizontal positions. Many accessories, or special devices applicable to particular uses, may be added to the microscope in its essential form, as a micrometer, polarizing prisms, camera lucida, etc. The compound microscope itself often varies widely in construction, according to the character of the work for which it is to be used. (Compare also the phrases below,)
2. n. [capitalized] A constellation. See Microscopium.
3. To enlarge with or as with a microscope; examine very minutely as with a microscope: as, to microscope one's faults.

Wiktionary

1. n. An optical instrument used for observing small objects.
2. n. Any instrument for imaging very small objects (such as an electron microscope).

GNU Webster's 1913

1. n. An optical instrument, consisting of a lens, or combination of lenses, for making an enlarged image of an object which is too minute to be viewed by the naked eye.

WordNet 3.0

1. n. magnifier of the image of small objects