When I first learned of Samadhi, I immediately assumed it was synonymous with Enlightenment. And although the term is used differently between the various traditions (Hindu, Buddhism, Yogic), the yogic understanding of Samadhi not necessarily equivalent to the big E.
In Patanjali’s Yoga Sutras, Samadhi is the eighth and final limb. After one has crossed the bridge form the externally focused limbs to the internally focused ones, the practitioner begins through the stages of attention. The withdrawal of the senses begins this inward journey. Attention itself will lead to dharana, which leads to dhyana, and finally to samadhi. Once Samadhi is experienced, a total absorption where only the essence of the object, place, or point will shine in the mind. The mind will lose form. Without this linear journey inward, the mind will create an internal battle leading to frustration.
However, the journey to samadhi will almost certainly cycle between what one would consider to be good or consider to be bad. Samadhi attainment through meditation can be used as a tool along the way, but not as the end itself.