(... Descending from trust/beneficence to renunciation/total enmity; any individual's understanding lies somewhere along this continuum...)
Psychiatry is a medical specialty which cures "mental illnesses" which are in fact diseases of the brain.
Pschiatry is the study, diagnosis and treatment of mental disorders, which include various affective, behavioral, cognitive and perceptual disorders.
Psychiatry is the medical treatment of socially problematic or dangerous human deviance.
Psychiatry is social control by various means and technologies traditionally considered to be medical, backed up by the coercive power of the state.
Psychiatry is the attempted, usually temporary and wildly unpredictable, iatrogenic disabling of unwanted behavior, whereby one more powerful person imposes "treatment" upon another weaker person; this is justified by medical metaphor.
Psychiatry is the forcible violation of personhood, and an attempt to destroy all concept of individual responsibility.