See also Significant Harm.
In relation to children:
Harm is defined by the Children Act 1989 as the ill treatment or impairment of health and development. This definition was clarified in section 120 of the Adoption and Children Act 2002 (implemented on 31 January 2005) so that it may include, "for example, impairment suffered from seeing or hearing the ill treatment of another".
In relation to adults:
Harm is to be taken to include not only ill treatment (including Sexual Abuse and forms of ill treatment which are not physical) but also the impairment of or an avoidable deterioration in physical or mental health and the impairment of physical, intellectual, emotional, social or behavioural development. (No Secrets (DH/Home Office 2000)).