LINE OF ACTION: Surprised is defined by raised brows, widened eyes and a dropped jaw...in it's most neutral pose. It's as if the face doesn't know that to do with the bottom half, so it goes neutral and the jaw drops as the eyes take in what they see. If the surprise is a good one? The mouth will flex into a smiling open jaw or even an extreme oooo shape as if to say "ooooo! I love that!" If it's not a good surprise the expression moves more into shock with down turned corners.
DEFINITION: To encounter suddenly or unexpectedly; take or catch unawares. To attack or capture suddenly and without warning. To cause to feel wonder, astonishment, or amazement, as at something unanticipated. Something, such as an unexpected encounter, event, or gift, that surprises.