The term 'Bitter End' can be broken down into four crossword solutions: DEMISE (6 letters), NESS (4 letters), EXTREMITY (9 letters), and ULTIMATE (8 letters). DEMISE is defined as the end of life or existence, while NESS is a Scottish word for a headland or promontory. EXTREMITY refers to the furthest point or limit, and ULTIMATE is the last in a series or the final outcome. Together, these words form the phrase 'Bitter End, ' which is used to describe a situation that has reached its most difficult or extreme point.