(Latin: hearth, fireplace; fire, flame; central point, center)
The word "focus" was introduced into mathematics by Johannes Kepler in 1604 with the meaning of any "central point".
2. Embodying two distinct and often conflicting goals, interests, or courses of action: Bibocals are eyeglasses made with double lenses of different focuses so that the wearer may have one focus for distant vision and one of close focus for reading.
Other bifocal lenses are the flat-top Franklin type, or blended invisibly.
2. The production of a focused electron beam in a cathode-ray tube with the application of an electric field.
2. A method of focusing the cathode-ray beam to a fine spot by the application of electrostatic potentials to one or more elements of an electron lens system.
2. The distinctness or clarity of an image rendered by an optical system.
3. The state of maximum clarity of an image; such as, in focus or out of focus.
4. An apparatus used to adjust the focal length of an optical system in order to make an image distinct or clear; for an example, a camera with automatic focus.
5. A condition in which something can be clearly apprehended or perceived: Harry simply couldn't get the problem into focus.
6. In pathology, the region of a localized bodily infection or disease.
7. In geology, the point of origin of an earthquake.
8. Etymology: from New Latin, focus, "central point"; from Latin focus, "hearth, fireplace".
The New Latin use was introduced in a Latin text about astronomy in 1604 by the German astronomer and mathematician, Johann Kepler, with reference to the "burning point (at which heat rays meet) of a lens or mirror".
2. The act of bringing into focus or converging at a point.
3. The change in strength of the crystalline lens of the eye that permits clear vision to be achieved at various distances.
2. Focused or centered on the mother.