The term 'MOST THIRSTY' can be solved by the crossword solution 'DRIEST', which is a six-letter word. The term 'DRIEST' is an adjective that means having the least amount of moisture or liquid, and is often used to describe a desert or other arid environment. Therefore, the term 'MOST THIRSTY' can be interpreted as referring to a place or situation that is extremely dry and in need of water.