fos·ter 
(fôstər, fŏstər)
(fôstər, fŏstər)tr.v. fos·tered, fos·ter·ing, fos·ters
1. To bring up; nurture: bear and foster offspring. See Synonyms at nurture.
2. To promote the growth and development of; cultivate: detect and foster artistic talent. See Synonyms at advance.
3. To nurse; cherish: foster a secret hope.
adj.
1. Providing parental care and nurture to children not related through legal or blood ties: foster parents; foster grandparents; a foster home.
2. Receiving parental care and nurture from those not related to one through legal or blood ties: foster children.
[Middle English fostren, from Old English *fōstrian, to nourish, from fōstor, food, nourishing; see pā- in the Appendix of Indo-European roots.]