A call sounded on a bugle, announcing to skirmishers that they are to retire, or fall back.
Origin
From Middle French retirer, from prefix re-, + verb tirer, from Old French tirer, tirier, from tire, tiere of Germanic origin, akin to Old English and Old Saxon Old Saxon tīr, Old English tīer, Old High German ziari, zēri, German German Zier, zieren. More at tier.