Daydream
Daydreaming is a stream of consciousness that detaches from current, external tasks when attention drifts to a more personal and internal direction.
There are various names of this phenomenon including mind-wandering, fantasy, spontaneous thoughts, etc. There are many types of daydreams, however the most common characteristic to all forms of daydreaming meets the criteria for mild dissociation. Also, the impacts of different types of daydreams are not identical. While some are disruptive and deleterious, others may be beneficial in some way.
Daydreaming is the term used by Jerome L. Singer, whose research laid the foundation for nearly all the subsequent research today. The terminologies assigned by researchers today puts challenges on identifying the common features of daydreaming, and on building collective work among researchers.