Acrimonious (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">acrimonious</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that acrimonious can be written as bitter)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for bitter that I've seen before include "Acerbic" , "Resentful or angry through disappointment" , "drink" , "Unpalatable; a beer" , "Resentful about English beer?" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">acrimonious</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for rancorous that I've seen before include "Resentful, bitter" , "Acrimonious" , "Showing bitter resentment" , "spiteful?" .)