The term 'MOST SORE' can be solved by two crossword solutions: ACHIEST (7 letters) and TENDEREST (9 letters). ACHIEST is an adjective that means 'most painful or sore'. It is derived from the word 'ACHE', which is a dull, continuous pain. TENDEREST is also an adjective that means 'most sore or sensitive'. It is derived from the word 'TENDER', which is used to describe something that is easily hurt or damaged.