surprisal

A surprise attack or ambush; a sudden or unexpected assault.

Their chiefe attempts are by Stratagems, trecheries, or surprisals.

A sudden coming-upon someone or something unexpectedly or unawares.

How to secure the lady from surprisal

Because death is uncertain, let us prevent its surprisal.

A surprising event or occurrence.

The feeling caused by being surprised; surprise, shock, amazement.

An information measure as equal in bits (binary digits) to the base-2 log of 1 over the probability, with the result that the number of choices equals 2ⁿ where n is the number of bits.