Aye, Aye! is a phrase used to express agreement or acknowledgement. It is commonly used in the military and nautical contexts, where it is used to signify that an order has been received and will be carried out. The crossword solutions YES (3 letters), SIR (3 letters), and LEMUR (5 letters) are all related to this phrase. YES is a common affirmative response, SIR is a term of respect used when addressing a superior, and LEMUR is an animal known for its vocalizations, which can sound like 'aye, aye'.