O.E.
*fostrian "to supply with food, nourish, support," from
fostor "food, nourishment, bringing up," from P.Gmc.
*fostrom, from root
*foth-/*fod- (see
food). Meaning "to bring up a child with parental care" is from c.1205; that of "to encourage or help grow" is c.1225 of things; 1570 of feelings, ideas, etc. O.E. also had the adj. meaning "in the same family but not related," in
fostorfæder, etc.