regression

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Reversion; retrogression.
2. n. Relapse to a less perfect or developed state.
3. n. Psychology Reversion to an earlier or less mature pattern of feeling or behavior.
4. n. Medicine A subsidence of the symptoms or process of a disease.
5. n. Biology The return of a population to an earlier or less complex physical type in successive generations.
6. n. Statistics The relationship between the mean value of a random variable and the corresponding values of one or more independent variables.
7. n. Astronomy Retrograde motion of a celestial body.
8. n. Geology A relative fall in sea level resulting in deposition of terrestrial strata over marine strata.

Century Dictionary and Cyclopedia

1. n. The act of passing back or returning; retrogression.
2. n. In astronomy, motion from east toward west.
3. n. In geometry, contrary flexure; also, the course of a curve at a cusp.
4. n. In mathematics, a discrete series which has a last element but no first.
5. n. In statistics, the tendency of one variable phenomenon that is correlated with another to revert to the general type and not to equal the amount of deviation of the particular phenomenon with which it is correlated. This tendency is measured by the coefficient of regression. An example of regression is furnished by the sons of a series of fathers having a certain stature which deviates from the typical stature of the people to which the fathers and sons belong. Then the statures of the sons will vary not around the stature of their fathers, but around another value which is nearer the typical stature of the people to which the series belongs. The proportion between the average deviation of the sons and the deviation of the fathers is the index of regression. In the same way an index of regression may be established between sizes of correlated parts of the same organism, or between any two correlated variables. See correlation, 5.
6. n. In breeding, the decline toward mediocrity of offspring from the mean of the two parents. Sometimes called filial regression.

Wiktionary

1. n. An action of regressing, a return to a previous state.
2. n. psychotherapy A psychotherapeutic method whereby healing is facilitated by inducing the patient to act out behaviour typical of an earlier developmental stage.
3. n. statistics An analytic method to measure the association of one or more independent variables with a dependent variable.
4. n. statistics An equation using specified and associated data for two or more variables such that one variable can be estimated from the remaining variable(s).
5. n. programming The reappearance of a bug in a piece of software that had previously been fixed.

GNU Webster's 1913

1. n. The act of passing back or returning; retrogression; retrogradation.

WordNet 3.0

1. n. an abnormal state in which development has stopped prematurely
2. n. (psychiatry) a defense mechanism in which you flee from reality by assuming a more infantile state
3. n. the relation between selected values of x and observed values of y (from which the most probable value of y can be predicted for any value of x)
4. n. returning to a former state