means A bugle call sounded at military funerals and at the end of the day to signal lights-out, marking sleep or final rest.

from The name comes from the older drum signal 'taptoo' or 'tattoo' — itself from the Dutch 'taptoe,' literally 'tap shut,' the command to close the taps of beer barrels in taverns so soldiers would head back to quarters for the night. That nightly 'tap to' shrank to 'taps.' The familiar 24-note bugle melody, though, is American: it was reworked during the U.S. Civil War in the 1860s, reportedly by a Union general and his brigade bugler, who softened an existing call into the version still played today.