https://en.oxforddictionaries.com/definition/psychosis

"A severe mental disorder in which thought and emotions are so impaired that contact is lost with external reality"

http://www.webmd.com/schizophrenia/guide/what-is-psychosis#1

"When you lose touch with reality and see, hear, or believe things that aren’t real, doctors call that psychosis."

I have my DSM-IV packed away, but I am sure you have it and/or the DSM-V handy.