Regenestasis was a passive state in which a Borg drone might find itself.
Aboard a Borg cube that had undergone a submatrix collapse, a Nameless drone was found that had been in regenestasis for fourteen years. (PIC: "Maps and Legends")
While Borg like these were unconscious, they might still respond to soothing stimuli. ("The End is the Beginning")
The name suggests two previously established concepts: regeneration and stasis.