Define Plain Meaning

the quality of vision. often accompanied by strong emotions. can, will lead to rational realisation. and - if balls are attached to your guts - to action.

How New Yorkers refer to a plain slice of cheese pizza.

someone who may be normal or boring.

nothing is really going on for them. physically just average features not ugly or pretty.
mentally just not exciting to talk to, dont do much cool stuff.

The best flavor of any tasty treat.

11th On Nirvana's Album "Nevermind"

No sense of the world around he/she when asked a simple ass question

A small village near Airdrie in North Lanarkshire, Scotland.

Look up "Airdrie" on urbandictionary.com, Plains is mostly similar.
Although Plains now has a train line running through it, unlike Airdrie and nearby village of Caldercruix it does not have a station. This is entirely due to the decision made by Network Rail against Plains.
However, due to tickets on the Airdrie>Bathgate line being ridiculously expensive, very few people are actually using the railway so Network Rail are getting their comeuppance.

the country side of halifax, where babys become men by learning how to ride dirt bikes and four wheelers at the young age of fetus, and a couple years down the road they become potheads and alcoholics. like a dude wearing black airforces, these people are no-one to piss off as you'll probably get your ass kicked.

Plaine service is defined as the service aboard a budget flight in which extra services,such as food & beverage and entertainment, are not provided or provided gratis.

'70s CB slang for an unmarked police car, usually used with the color of the car between "plain" and "wrapper."