fos·ter / ˈfôstər; ˈfäs-/ • v. [tr.] 1. encourage or promote the development of (something, typically something regarded as good): the teacher's task is to foster learning. ∎ develop (a feeling or idea) in oneself: appropriate praise helps a child foster a sense of self-worth. 2. bring up (a child that is not one's own by birth).• adj. denoting someone that has a specified family connection through fostering rather than birth: foster parent foster child. ∎ involving or concerned with fostering a child: foster care foster home.DERIVATIVES: fos·ter·age / -rij/ n.fos·ter·er n.