Samsara means to be trapped in the unending cycle of birth and death in which no apparent escape is discernible. Everything in between the time of our birth and our eventual death is samsara which I hasten to add, doesn't end with our death. Even if we hope for nirvana there is still only samsara. The trap is almost perfect. The only escape is by the realization of true Mind (pure Mind, bodhi Mind, etc.).
Even though the Buddha's carnal body and those of the realized master's crapped out, both were anchored in the deathless nature of true Mind. They could clearly discern (prajñâ) the immortal from the mortal. Death was unable to destroy true Mind.
Samsara is like a child making a sandcastle who is only aware of the castle, itself; who takes no cognizance of the sand from which the castle is made. When the ocean waves eventually destroy the child's castle, the child is in tears. The child doesn't see that the castle is nothing more than sand. It is just a configuration of sand, in other words, or the same, a dependent origination of sand. The birth of the sandcastle which results in its subsequent destruction is the creation of desire which ever seeks to transform the true into the false because of avidya (not knowing that the transformed is but a configuration of the true).
During meditation, we should observe that each and every thought or subtle feeling that arises in our psychophysical body, which the Buddha calls, “old karma”, is but a mind-castle! Our problem is that we don’t have a clue as to what all these mind-castles are composed from. We are clueless as to the substance (tathatâ).