pony

Etymology 1

1659 from Scots powny, apparently from Middle French poulenet (“little foal”), ultimately from Late Latin pullanus (“young of an animal”), from pullus (cognate to English foal). Sense “small serving of alcohol” from 19th century, both for small sizes generally and for a quarter pint specifically, from the small size.

noun

1. A small horse; specifically, any of several small breeds of horse under 14.2 hands at the withers.
2. a contraption built like a mount, strong enough to support one's weight
3. (regional) A small serving of an alcoholic beverage, especially beer.
   1879, “Some Queer Interviews: Interview with a Pony of Beer”, Puck, Vol. 5–6, p. 435
   ‘I’m on the inside track,’ said a pony of beer as it went galloping down a man’s throat. 1885, New York Journal, August
   Demon popped into his mouth a last morsel of black bread with elastic samlet, gulped down a last pony of vodka and took his place at the table with Marina facing him across its oblong length. 1969, Vladimir Nabokov, Ada or Ardor, Penguin, published 2011, page 193
   I did not even know what a ‘pony’, a small chaser of beer, was. But of course I could not admit that. So putting on an air of nonchalance, and a deep voice, I strolled into a pub with one of the other equally naive guys and we ordered two ponies of beer. ‘McEwans?’ asked the barman. ‘Naw - ponies’ said I. 2010, Dick Lynas, Pies Were for Thursdays: Tales from an Ordinary Glasgow East End Childhood, page 283
4. (Australia, New South Wales, Victoria, Western Australia) A serving of 140 millilitres of beer (formerly 5 fl oz); a quarter pint.
5. (UK, slang) Twenty-five pounds sterling.
   “Well—well—there’s the money, Sir Francis Clavering. […] Here’s five-and-twenty for you.
6. (US, slang) A translation used as a study aid; loosely, a crib, a cheat-sheet.
   She kept the dates written down in her Latin 'pony', so she didn't have to bother about who it was. 1931, William Faulkner, Sanctuary, Library of America, published 1985, page 104
7. (slang) A ponytail hairstyle.
   His hair is a semilong dull red and pulled back in a sloppy pony at the base of his neck, and his face is riddled with small freckles and grease, but out here I can see personal hygiene isn't exactly at the top of the priority list. 2012, Amlynn Smith, Lost and Found, page 18
8. (automotive, slang) One horsepower.
   How many ponies are under the hood?
9. (slang) A chorus girl of small stature.
   He suggested a Rose Ballet in which he would use the G. V. Follies chorus girls, chiefly the ponies and mediums. 1941, Thoda Cocroft, Great Names and how They are Made, page 140
10. (slang, derogatory, video games) Ellipsis of Sony pony.

verb

1. (transitive) To lead (a horse) from another horse.
2. To use a crib or cheat-sheet in translating.

Etymology 2

Clipping of pony and trap, rhyming with crap.

adj

1. (Cockney rhyming slang) Of little worth.

noun

1. (Cockney rhyming slang) Crap; rubbish, nonsense.