an unexpected presentation of a gift or good news; also one may expect to receive a gift, but does not know what: it is kept secret, because it is a surprise.
surprise attack or ambush: assault that is not expected by the victim, giving the attacker the advantage that no defense has been prepared, or that there is less alertness in applying the defense; thus it is essential to keep a plan for such an assault secret. Examples are the Attack on Pearl Harbor and September 11, 2001 Terrorist Attack;
