Old one.  The Devil.  Likewise an expression of quizzical
  familiarity, as “how d’ye do, old one?”

Old Pegg.  Poor Yorkshire cheese, made of skimmed
  milk.

Old POGER.  The Devil.

Old Stager.  One accustomed to business, one who knows
  mankind.

Old toast. A brisk old fellow.  Cant.

Old Doss.  Bridewell.

Oliver’s scull.  A chamber pot.

Olli COMPOLLI.  The name of one of the principal rogues
  of the canting crew.  Cant.

OMNIUM GATHERUM.  The whole together:  jocular imitation
  of law Latin.

One in ten.  A parson:  an allusion to his tithes.

One of us, or one of my cousins.  A woman of the
  town, a harlot.

Onion.  A seal.  Onion hunters, a class of young thieves
  who are on the look out for gentlemen who wear their
  seals suspended on a ribbon, which they cut, and thus
  secure the seals or other trinkets suspended to the watch.

Open arse.  A medlar.  See medlar.

OPTIME.  The senior and junior optimes are the second
  and last classes of Cambridge honors conferred on taking
  a degree.  That of wranglers is the first.  The last
  junior optime is called the Wooden Spoon.

Organ.  A pipe.  Will you cock your organ? will you
  smoke your pipe?

Orthodoxy and heterodoxy.  Somebody explained these
  terms by saying, the first was a man who had a doxy of
  his own, the second a person who made use of the doxy
  of another man.

OSCHIVES.  Bone-handled knives.  Cant.

Ostler.  Oatstealer.

OTTOMY.  The vulgar word for a skeleton.

OTTOMISED. To be ottomised; to be dissected.  You’ll be
  scragged, ottomised, and grin in a glass case:  you’ll be
  hanged, anatomised, and your skeleton kept in a glass
  case at Surgeons’ Hall.

Oven.  A great mouth; the old woman would never have
  looked for her daughter in the oven, had she not been there
  herself.

Overseer.  A man standing in the pillory, is, from his
  elevated situation, said to be made an overseer.

Out at heels, or out at elbows.  In declining circumstances.

Outrun the constable.  A man who has lived above his
  means, or income, is said to have outrun the constable.

Outs.  A gentleman of three outs.  See gentleman.

Owl.  To catch the; a trick practised upon ignorant country
  boobies, who are decoyed into a barn under pretence
  of catching an owl, where, after divers preliminaries, the
  joke ends in their having a pail of water poured upon their
  heads.