craven n.  懦夫

---------coward
A hero risks his life to help others; a craven runs from the scene.  
    
trepidation n. 惊恐； 惶恐

-------nervous agitation; fear; fright; trembling 
I thought Carol would be nervous when she made her speech, but she delivered it without trepidation.  
   
cower vi.  （因恐惧，痛苦等）畏缩 

-------draw back trembling; shrink or crouch in fear; cringe; recoil 
Brave men defy tyrants, instead of cowering before them.  
   
intimidate vt. 胁迫； 威胁（某人做某事）

------make fearful or timid; frighten; force by fear; cow; bully 
The younger boys would not have given up the playing field so quickly if the older boys hadn't intimidated them.  
   
apprehensive adj. 不安的； 忧虑的
------expecting something unfavorable; afraid; anxious 
Several apprehensive parents telephoned the school when the children were late in getting home from the museum trip.  
   
dastardly adj. 欺善怕恶的； 懦弱的

-------cowardly and mean 
It was dastardly of the caption to desert the sinking vessel and leave the passengers to fend for themseves.  
   
timid adj. 胆怯的 

-----lacking courage or self-confidence; fearful; timorous; shy 
If the other team challengers us, we should accept. Let's not be so timid!