I realize that many people use "chickenshit" as a synonym or intensified version of the slang "chicken," but this is a misuse. "Chickenshit" is a play on the word "bullshit," and people who use it otherwise are mistaken.
I also realize many people think that nobody ever uses a word wrongly, that words mean whatever a given user means by them, whatever they appear to mean by context, etc. I am not one of those people. :) See "peruse" for a similar case of a word that is commonly used incorrectly, but has a real meaning supported by its etymology. Silarius