Dhyana literally means “contemplation, reflection” and “profound, abstract meditation”.
Dhyana is contemplating, reflecting on whatever Dharana has focused on. If in the sixth limb of yoga one focused on a personal deity, Dhyana is its contemplation. If the concentration was on one object, Dhyana is non-judgmental, non-presumptuous observation of that object.If the focus was on a concept/idea, Dhyana is contemplating that concept/idea in all its aspects, forms and consequences. Dhyana is uninterrupted train of thought, current of cognition, flow of awareness.
Dhyana is integrally related to Dharana, one leads to other. Dharana is a state of mind, Dhyana the process of mind. Dhyana is distinct from Dharana in that the meditator becomes actively engaged with its focus. Patanjali defines contemplation (Dhyana) as the mind process, where the mind is fixed on something, and then there is “a course of uniform modification of knowledge”.