The term 'SUPERLATIVELY secret' can be broken down into two crossword solutions: 'INNERMOST' (9 letters) and 'SUPERLATIVELY' (11 letters). The word 'INNERMOST' is an adjective that means the farthest or deepest within, while 'SUPERLATIVELY' is an adverb that means to the highest degree. Together, the two words describe something that is extremely hidden or concealed. This phrase is often used to describe something that is kept very private or confidential.