LINE OF ACTION: Fear involves a furrowed/worried brow that is also raised and an unhappy mouth - either open or closed. The final visual cue that determines fear from sadness is the wide-eyed shock pose of the eyes. If the fear is really intense, the furrow is pushed out to a completely raised brow.
DEFINITION: A feeling of agitation and anxiety caused by the presence or imminence of danger. A state or condition marked by this feeling: living in fear. A feeling of disquiet or apprehension: a fear of looking foolish. Extreme reverence or awe, as toward a supreme power. A reason for dread or apprehension: Being alone is my greatest fear. To be afraid or frightened of. To be uneasy or apprehensive about: feared the test results.