armpit: the hollow under the arm where it is joined to the shoulder
entity: that which is perceived or known or inferred to have its own distinct existence (living or nonliving)
fall of man: (Judeo-Christian mythology) when Adam and Eve ate of the fruit of the tree of knowledge of good and evil in the Garden of Eden, God punished them by driving them out of the Garden of Eden and into the world where they would be subject to sickness and pain and eventual death