1archaic Take off or lower (one's hat or crown) as a token of respect or submission.‘Turning himself towards the noblemen that sat on a form placed before the scaffold, he vailed his hat.’
- ‘He vailed his bonnet to no one but a judge.’
- ‘Vailing his cap, like them, to the Queen's representatives, he covered himself when he looked at the Pope's delegate.’
- 1.1no object Take off one's hat or otherwise show respect or submission to someone.
Middle English (originally in the sense ‘lower (one's eyes, weapon, banner, etc.) as a sign of submission’): shortening of obsolete avale, from Old French avaler ‘to lower’, from a val ‘down’ (literally ‘in the valley’).