Foster, v. t. [imp. & p. p. Fostered, p. pr. & vb. n. Fostering.]
Etymology: [OE. fostren, fr. AS. foster, fostor, food, nourishment, fr. foda food. *75. See Food.]
1. To feed; to nourish; to support; to bring up. Some say that ravens foster forlorn children. Shak.
2. To cherish; to promote the growth of; to encourage; to sustain and promote; as, to foster genius.
4 other Webster entries under this spelling
Foster, v. i.
To be nourished or trained up together. [Obs.] Spenser.
Foster, a.
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. Foster babe, or child, an infant of child nursed by a woman not its mother, or bred by a man not its father. -- Foster brother, 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. [Obs.] (b) One's adopted country. -- Foster lean Etym: [foster + AS. læn a loan See Loan.], remuneration fixed for the rearing of a foster child; also, the jointure of a wife. [Obs.] 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. [R.] Shak. -- Foster parent, a foster mother or foster father. -- Foster son, a male foster child.
Foster, n.
A forester. [Obs.] Spenser.
Foster, n.
One who, or that which, fosters.
Shades of meaning
Fernald has no entry of its own for foster; he lists it under cherish, help, promote.
Where he writes about it:
To nourish is strictly to sustain and build up by food; to nurture includes careful mental and spiritual training, with something of love and tenderness; to foster is simply to maintain and care for, to bring up; a foster-child will be nourished, but may not be as tenderly nurtured or as lovingly cherished as if one's own. — from cherish