A corruption of ensign—a flag and the officer who bore it. Pistol was Falstaff's “ancient.” “Ten times more dishonourably ragged than an old-faced ancient.” —Shakespeare: I Henry IV, iv. 21.
“My whole charge consists of ancients, corporals, lieutenants, gentlemen of companies...” —Shakespeare: I Henry IV, iv. 2.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
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