vail
/veɪl/verb
with obj.
1- archaic take off or lower (one's hat or crown) as a token of respect or submission〈古〉（表示敬意或顺从）放（或脱）下（帽, 冠）。
1.1
- no obj. take off one's hat or otherwise show respect or submission to someone脱帽致敬; 脱帽以示顺从。
词源
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'）.