The term 'NOT SO LOUD!' can be represented by three crossword solutions: SHH (3 letters), HOLDITDOWN (10 letters), and TONEITDOWN (10 letters). SHH is an interjection used to tell someone to be quiet, while HOLDITDOWN and TONEITDOWN are both phrases that mean to reduce the volume of one's voice. All three solutions suggest that the speaker wants the person they are addressing to lower their volume.