害児 is read as がいじ (gaiji) and means retard.
がいじ
gaiji
ちてきしょうがいじ
intellectually disabled child
しんたいしょうがいじ
physically disabled child
しんしんしょうがいじ
child with a physical or mental disability
がくしゅうしょうがいじ
child with a learning disability
しょうがいじ
child with a (physical or mental) disability
じょうしょしょうがいじ
emotionally disturbed child
しょうがいじきょういく
education of children with disabilities
しょうがいじがっきゅう
special class for disabled children
がいちゅう
harmful insect
しょうじ
young child
いくじ
childcare
こ
-er (often of young women)