I. fos ‧ ter 1 /ˈfɒstə $ ˈfɑːstər/ BrE AmE verb
1 . [transitive] to help a skill, feeling, idea etc develop over a period of time SYN encourage , promote :
The bishop helped foster the sense of a community embracing all classes.
2 . [intransitive and transitive] to take someone else’s child into your family for a period of time but without becoming their legal parent ⇨ adopt :
The couple wanted to adopt a black child they had been fostering.
II. foster 2 BrE AmE adjective
[ Language: Old English ; Origin: fostor- , from fostor 'food, feeding' ]
1 . foster mother/father/parents the people who foster a child:
It is sometimes difficult to find suitable foster parents.
2 . foster child/son/daughter a child who is fostered
3 . foster brother/sister someone who has different parents from you, but who is being brought up in the same family
4 . foster home a private home where a child is fostered