The Collaborative International Dictionary of English v.0.48:
Surprisal \Sur*pris"al\, n. [See Surprise, n.] The act of surprising, or state of being surprised; surprise. [1913 Webster] How to secure the lady from surprisal. --Milton. [1913 Webster] Because death is uncertain, let us prevent its surprisal. --Barrow. [1913 Webster]WordNet (r) 3.0 (2006):
surprisal n 1: the act of surprising someone [syn: surprise, surprisal]