- 1. The special action or physiologic property of an organ or other part of the body. 2. To perform its special work or office, said of an organ or other part of the body. 3. The general properties of any substance, depending on its chemical character and relation to other substances, according to which it may be grouped among acids, bases, alcohols, esters, etc. 4. A particular reactive grouping in a molecule; e.g., a functional group, such as the –OH group of an alcohol. 5. A quality, trait, or fact that is so related to another as to be dependent upon and to vary with this other. 6. A mathematical variable or expression. [L. functio, fr. fungor, pp. functus, to perform]- allomeric f. the combined f. of the several segments of the spinal cord and medulla, communicating with each other by means of the white matter.- atrial transport f. the role of the atria in filling and stretching the ventricles by their presystolic contraction, without which the force of ventricular contraction and hence the cardiac output may significantly decrease.- discriminant f. a particular combination of continuous variable test results designed to achieve separation of groups; e.g., a single number representing a combination of weighted laboratory test results designed to discriminate between clinical classes.- line spread f. (LSF) a measure of the ability of a system to form sharp images; in radiology, determined by measuring the spatial density distribution on film of the x-ray image of a narrow slit in a dense metal, such as uranium; from this can be calculated the modulation transfer f..- modulation transfer f. (MTF) in testing radionuclide detectors or radiographic systems, the efficiency, at each spatial frequency, of reproducing the variation (contrast) in the object density or signal in the image; it is an expression of spatial resolution and is used to evaluate imaging systems and their components; the integral of the line spread f.; also known as the frequency response f. or contrast transmission f.; usually given as a plot of percentage amplitude response versus frequency in cycles per millimeter.
* * *func·tion 'fəŋ(k)-shən n any of a group of related actions contributing to a larger action esp the normal and specific contribution of a bodily part to the economy of a living organism see vital functionfunc·tion·less -ləs adjfunction vi, func·tioned; func·tion·ing -sh(ə-)niŋ to have a function <shivering \functions to maintain the heat of the body>
* * *func·tion (funkґshən) [L. functio, from fungi to do] 1. the special, normal, or proper physiologic activity of an organ or part. 2. to perform such activity. 3. in chemistry, a characteristic behavior of a chemical compound due to the presence of a specific functional group (q.v.) 4. in mathematics, a rule that assigns to each member of one set (the domain) a value in another set (the range).
Medical dictionary. 2011.