surprise (n.) Look up surprise at Dictionary.com
mid-15c., "unexpected attack or capture," from M.Fr. surprise "a taking unawares," from noun use of pp. of O.Fr. surprendre "to overtake," from sur- "over" + prendre "to take," from L. prendere, contracted from prehendere "to grasp, seize" (see prehensile). Meaning "something unexpected" first recorded 1590s, that of "feeling caused by something unexpected" is c.1600. Meaning "fancy dish" is attested from 1708.
"A Surprize is ... a dish ... which promising little from its first appearance, when open abounds with all sorts of variety." [W. King, "Cookery," 1708]
The verb is from late 15c. Surprise party originally was a military detachment (1841); festive sense is attested from 1858. Related: Surprising; surprisingly.