absol. To lower sail, haul down one's flag; esp. to lower the topsails or haul down the flag or colours as a sign of surrender or as a salute.

esp. To lower as a salute or in acknowledgement of inferiority. Chiefly with bonnet as object. Sometimes figurative. (Cf. 2b.)

In various nautical phrases, as to give (deny, refuse,etc.) the honour of the flag: to make (or refuse) an acknowledgement of supremacy by striking…