The term 'buttoned up' can be defined by four crossword solutions: 'UNCOMMUNICATIVE' (15 letters), 'CARDIGAN' (8 letters), 'MUM' (3 letters), and 'asquietasamouse' (15 letters). UNCOMMUNICATIVE means to not communicate or talk, which is often associated with being buttoned up. A CARDIGAN is a type of sweater that is usually buttoned up, and 'MUM' is a British term for being silent or not speaking. Lastly, 'asquietasamouse' is an idiom meaning to be very quiet, which is another way of saying buttoned up.