foster

¹ American  

[faw-ster, fos-ter] / ˈfɔ stər, ˈfɒs tər /

verb (used with object)

1. to promote the growth or development of; further; encourage.

   to foster new ideas.

   Synonyms:

   instigate, foment, advance, forward, favor

   Antonyms:

   discourage

2. to care for a foster child or a pet as a temporary guardian.

   The couple fostered two boys until they could be reunited with their birth parents.

   Have you ever fostered a kitten that you just couldn’t part from afterwards?

   Synonyms:

   maintain, support, sustain, nourish, nurse

3. to care for or cherish.

4. British. to place (a child) in a foster home.

5. Obsolete. to feed or nourish.

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Foster ² American  

[faw-ster, fos-ter] / ˈfɔ stər, ˈfɒs tər /

noun

1. Stephen (Collins), 1826–64, U.S. songwriter.

2. William Z(ebulon) 1881–1961, U.S. labor organizer: leader in the Communist Party.

3. a male given name.

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foster ¹ British  

/ ˈfɒstə /

verb

1. to promote the growth or development of

2. to bring up (a child, etc); rear

3. to cherish (a plan, hope, etc) in one's mind

4. 1. to place (a child) in the care of foster parents

   2. to bring up under fosterage

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adjective

1. (in combination) indicating relationship through fostering and not through birth

   foster mother

   foster child

2. (in combination) of or involved in the rearing of a child by persons other than his natural or adopted parents

   foster home

Foster ² British  

/ ˈfɒstə /

noun

1. Jodie . born 1962, US film actress and director: her films include Taxi Driver (1976), The Accused (1988), The Silence of the Lambs (1990), Little Man Tate (1991; also directed), Nell (1995), and Panic Room (2002)

2. Norman , Baron. born 1935, British architect. His works include the Willis Faber building (1978) in Ipswich, Stansted Airport, Essex (1991), Chek Lap Kok Airport, Hong Kong (1998), the renovation of the Reichstag, Berlin (1999), and City Hall, London (2002)

3. Stephen Collins . 1826–64, US composer of songs such as The Old Folks at Home and Oh Susanna

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Related Words

See cherish.

Other Word Forms

• fosterer noun
• fostering noun
• fosteringly adverb
• unfostering adjective

Etymology

Origin of foster

First recorded before 1000; Middle English; Old English fōstor “nourishment,” fōstrian “to nourish”; cognate with Old Norse fōstr; akin to food

Explanation

To foster is to nurture something. A teacher could foster creativity by providing crayons to every student. You can also foster a child, which means the child lives in your home for a time. You may have seen photos of a cat taking care of a baby rabbit, or a pig nursing a litter of puppies: those are little foster families. Foster can be a verb (to foster someone or something) or an adjective used to describe a foster family, child, or parent. The word is from the Old English fostrian meaning "to supply with food, nourish, support," which sounds like what those mama hogs were doing. Unlike adopt, foster has a time limit.

Example Sentences

Outside Parmelee Avenue Elementary in the Florence-Firestone neighborhood Wednesday morning, a woman with three foster children said the boys, two of whom are autistic, were new to the school and adjusting to a new routine.

From Los Angeles Times • Apr. 10, 2026

In reinforcing the energy vs. environment narrative, this decision could hinder efforts to foster conservation in the energy industry.

From Salon • Apr. 7, 2026

Another longtime observer of IPOs, the University of Florida professor Jay Ritter, also thinks the 15-day fast entry to the Nasdaq 100 will foster a kind of slow-motion flipping.

From Barron's • Apr. 1, 2026

He pointed an audience of several hundred people to his contributions to a project called Shaping AI, a collaboration among researchers and academics meant to foster conversation about how AI is used.

From The Wall Street Journal • Mar. 29, 2026

We’d been in foster care for just a few months when my grandfather appeared on Miss Doris and Mr. Leo’s doorstep.

From "Courage to Soar" by Simone Biles