regression

noun

re·​gres·​sion ri-ˈgre-shən 

1

: the act or an instance of regressing

2

: a trend or shift toward a lower or less perfect state: such as

a

: progressive decline of a manifestation of disease

b(1)

: gradual loss of differentiation and function by a body part especially as a physiological change accompanying aging

(2)

: gradual loss of memories and acquired skills

c

: reversion to an earlier mental or behavioral level

d

: a functional relationship between two or more correlated variables that is often empirically determined from data and is used especially to predict values of one variable when given values of the others

the regression of y on x is linear

specifically : a function that yields the mean value of a random variable under the condition that one or more independent variables have specified values

3

: retrograde motion

Synonyms

• reversion

Examples of regression in a Sentence

the regression to really childish behavior that boys often undergo when put in large groups

Recent Examples on the Web

This includes scalable infrastructure that runs red team evaluations on every model update, integrating with CI/CD pipelines to catch possible regressions before deployment. —David Talby, Forbes.com, 2 Sep. 2025

Galton, who coined the term eugenics, pioneered correlation and regression and used these tools to argue that traits like intelligence and morality were heritable and should be managed through selective breeding. —Craig Spencer, The Atlantic, 29 Aug. 2025

After giving up three out of four games in their latest series against the Boston Red Sox, the Yankees still hold a multi-game lead over the Kansas City Royals for a playoff spot, despite numerous injuries and surprising regressions for their star players. —Peter Chawaga, MSNBC Newsweek, 25 Aug. 2025

Maresca’s side found the net 64 times in 38 games last season, one of the few areas that saw significant regression from Mauricio Pochettino’s sole campaign in charge (which yielded 77 goals scored). —Liam Twomey, New York Times, 20 Aug. 2025

Word History

First Known Use

1583, in the meaning defined at sense 1

Phrases Containing regression

• linear regression
• multiple regression

Rhymes for regression

• accession
• aggression
• compression
• concession
• confession
• depression
• digression
• discretion
• expression
• impression
• obsession
• oppression

Kids Definition

regression

noun

re·​gres·​sion ri-ˈgresh-ən 

: an act or the fact of regressing

Medical Definition

regression

noun

re·​gres·​sion ri-ˈgresh-ən 

: a trend or shift toward a lower, less severe, or less perfect state: as

a

: progressive decline (as in size or severity) of a manifestation of disease

tumor regression following radiation

b(1)

: a gradual loss of differentiation and function by a body part especially as a physiological change accompanying aging

menopausal regression of the ovaries

(2)

: gradual loss (as in old age) of memories and acquired skills

c

: reversion to an earlier mental or behavioral level or to an earlier stage of psychosexual development in response to organismic stress or to suggestion

a protective regression towards childhood

—Havelock Ellis