Webster's Revised Unabridged Dictionary · 1913

Foster

Foster , transitive verb

[Old English fostren, from Anglo-Saxon fōster, fōstor, food, nourishment, from fōda food. r75. See Food.]

1.
To feed; to nourish; to support; to bring up.
Some say that ravens foster forlorn children. — Shakespeare
2.
To cherish; to promote the growth of; to encourage; to sustain and promote; as, to foster genius.

Foster , intransitive verb

To be nourished or trained up together. [Obsolete] — Spenser

Foster , adjective

[Anglo-Saxon fōster, fōstor, nourishment. See Foster, transitive verb]

Relating to nourishment; affording, receiving, or sharing nourishment or nurture; -- applied to father, mother, child, brother, etc., to indicate that the person so called stands in the relation of parent, child, brother, etc., as regards sustenance and nurture, but not by tie of blood.
Collocations (11)
Foster babe or Foster child , an infant or child nursed or raised by a woman not its mother, or bred by a man not its father.
Foster brother or Foster sister , one who is, or has been, nursed at the same breast, or brought up by the same nurse as another, but is not of the same parentage.
Foster dam , one who takes the place of a mother; a nurse. — Dryden
Foster earth , earth by which a plant is nourished, though not its native soil. — J. Philips
Foster father , a man who takes the place of a father in caring for a child. — Bacon
Foster land , (a) Land allotted for the maintenance of any one. [Obsolete] (b) One's adopted country.
Foster lean , remuneration fixed for the rearing of a foster child; also, the jointure of a wife. [Obsolete] — Wharton
Foster mother , a woman who takes a mother's place in the nurture and care of a child; a nurse.
Foster nurse , a nurse; a nourisher. [Rare] — Shakespeare
Foster parent , a foster mother or foster father.
Foster son , a male foster child.

Foster , noun

A forester. [Obsolete] — Spenser