Psychosis is a derived term. Psych is an ancient Greek term for that which exists because of, or in relation to, the mind, the activity of the brain. The suffix -osis implies an ongoing, a possibly changing, state. Psychosis therefore is a reference to an "Ongoing state of the mind" and can be an accurate description of imagination and/or hallucination. This differs from Psychotic which, with the suffix -otic, describes an un-changing state of the mind, most often used to describe drugs which affect the mind without exception or a period of hallucination in the past, a psychotic drug or a pyschotic "episode" (a period in which the ideas of the mind do not match reality). The mind is not the brain. The brain exists without function. The mind is produced by the brain, most likely in conjunction with the nervous system.
The idea of the psyche (sigh key), that based in thought, dates back to the time when the Greek language was very common in Europe, several thousand years ago. All persons think with their mind regardless of communicative ability or disability. If the brain ceases to function and produce a mind, the body ceases to function therefore the mind is an indistinguishable part of life for any organism capable of producing a mind (anything which has a brain only lives so long as the brain functions).
That which is physical exists with or without the mind. The mind is aware of that which is reality through the body and the five senses, sight. sound, touch, taste and smell. The body's ability to sense may become impaired and the minds ability to register the senses may become impaired. The mind may also imagine sensation. In these situations, that which does not exists in reality can be believed to exist by the mind. Psychosis can include sight, sound, touch, taste, smell and other imagined senses such as the ability to interpret another mind, to make thoughts *audible*, to have one's thoughts interpreted, to touch or taste objects without physical contact or to smell that which does not produce an odour within a detectable range.