1610s, "attacked unexpectedly," past-participle adjective from surprise (v.). Meaning "excited by something unexpected" is from 1882.
Entries linking to surprised
surprise v.
also formerly surprize, late 14c., "overcome, overpower" (of emotions), from the noun or from Anglo-French surprise, fem. past participle of Old French surprendre (see surprise (n.)). Meaning "come upon unexpectedly" is from 1590s; that of "strike with astonishment" is 1650s.