noun

• (UK, chiefly Northern England, New Zealand, Ireland) A sandwich, usually with a hot or cold savoury filling buttered in a barmcake. The most common are chips, bacon, sausage and egg.
  "Let's have a bacon butty!"

noun

• (colloquial, UK, now chiefly Wales and West Country) A friend.
• (mining) A miner who works under contract, receiving a fixed amount per ton of coal or ore.
  "But Alfred Charlesworth did not forgive the butty these public-house sayings. Consequently, although Morel was a good miner, sometimes earning as much as five pounds a week when he married, [...]"
• (colloquial, UK) A workmate.
• (archaic, UK dialect, among boys) A drudge; a cat's paw; someone who does the hard work; someone who is being taken advantage of by someone else.
  "Ah didn't play butty, ah promise yer. Yo all on yer mek the poor lad yer butty."

verb

• (archaic, UK dialect) To work together; to keep company with.
  "I butty with Jackson."
• (archaic, Shropshire) To cohabit; to reside with another as a couple.
  "Did'n'ee 'ear as Jim Tunkiss brought three children to the parish? I reckon 'e inna married, but 'e's bin buttyin' along o' one o' them Monsells."
• (archaic, Yorkshire) To act in concert with intent to defraud; to play unfairly.

adj

• (dated, Ireland and West Country) Resembling a heavy cart.
  "Shall it be a giggy thing, or a carty thing, or a butty thing?"