Def.- informal speech or writing; being more approprate for spoken language than written language.
Syn.- informal, nonstandard, slang, vulgar
""Oh," said the corporal. He linked his arm in the youth's and drew him foward. "Come on Henry. I'll take keer' a yah." As they went on together, the loud private called out for them. "Put 'im t' sleep in my blanket, Simpson. An'- hol' on a minnit - here's my canteen. It's full 'a coffer. Look at his head by th' fire an' see how it looks Maybe it's a pretty bad 'un. When i git relieve in a couple 'a minnits, i'll be over 'an see t' him."
-The Red Badge of Courage, Stephen Crane
This passage contains a colloquial tone. Grammer used here won't be found in proper writing. There is a bunch of onomatopoeia words and apostrophes in places of certain letters. It is more comprehensible if it was spoken to you than if you read it.Also, you wouldn't find it a bit strange if it was spoken.