child, kid, minor, nipper, tiddler, youngster, tike, tyke, shaver, small fry, nestling, fry - a young person of either sex; "she writes books for children"; "they're just kids"; "`tiddler' is a British term for youngsters"

foster-daughter - someone who is raised as a duaghter although not related by birth

foster-son - someone who is raised as a son although not related by birth