Arupavacara Citta
There are 12 arupavacara cittas.
They can be divided into three groups according to their origin or jati.
They are
4 arupakusala cittas are cittas that arise when arupa jhana are being practised.
The practice of arupa jhana is bhavana kusala.
So at the time of arupa jhana, arupakusala cittas arise.
Where the practitioner is an arahat, then the arising arupa jhana are called arupakiriya cittas.
Kiriya citta does not give rise to kammic force or seed effect.
Kusala citta gives vipaka or resultant cittas.
The practice of arupa jhana may give rise to rebirth in arupa brahma bhumi.
4 arupavipaka cittas are resultant cittas due to respective arupakusala citta.
These 4 cittas arise only in arupa brahma.
Because they all are patisandhi citta, bhavanga citta, and cuti citta of arupa brahma.
So they cannot arise in other planes of existence.
These 12 cittas arise mostly in arupa brahma bhumi.
So they are called arupavacara cittas.
Arupa here means arupa brahma bhumi or arupa brahma realm or formless realm.
Source
http://www.wisdomlib.org/definition/arupavacara-citta/index.html
