Definition of "exes"

It is not unknown for a logician to talk about exes and wyes.

1997, John Trotter, System of Rational Discourse, page 22

The betting also began to shift. "Sixpence Ned wins!" cried three or four; "Sixpence he loses!" answered another; "Done!" and up went the halfpence. "Half-a-crown Joe loses!"—"Here you are," answered Joe, but he lost again. "I'll try you a 'gen'" (shilling) said a coster; "And a rouf yenap'" (fourpence), added the other. "Say a 'exes'" (sixpence).—"Done!" and the betting continued, till the ground was spotted with silver and halfpence.

1851, Henry Mayhew, “Gambling of Costermongers”, in London Labour and the London Poor‎, volume 1, page 17

Subs at the Star even had their own monthly exes (expenses), and we never even left the office. We got exes for our home phone calls and even our own supply of daily newspapers; in our view, most reporters made their exes up.

2012, Jeff Connor, Field of Fire

The news-booze axis was reinforced by the fact that most of the meals and drinks were covered by 'exes' — expenses. […] One day perhaps there will be Freedom of Information on newspapers (and judges) and we shall be surprised at what is claimed as exes.

2014, Denis MacShane, Prison Diaries