Transientity
transient
[Alteration of Latin trnsins, trnseunt- present participle of trnsre,
"to go over" : trns-, over; see trans- + re, to go; see ei- in
Indo-European Roots.]

entity
[Medieval Latin entits, from Latin ns, ent- present participle of esse,
"to be". See es- in Indo-European Roots.]

{thnx to smrs}