The term 'Quiet One' can be described by three crossword solutions: SHY (3 letters), CLAM (4 letters), and MOUSE (5 letters). All three words refer to someone who is not very vocal or outspoken, and instead prefers to keep to themselves. The word 'SHY' implies a timidness or bashfulness, while 'CLAM' suggests someone who is silent and secretive. Finally, the word 'MOUSE' implies someone who is meek and unassuming. All three words together paint a picture of someone who is introverted and prefers to stay out of the spotlight.