The forms required by good breeding, or prescribed by authority, to be observed in social or official life; observance of the proprieties of rank and occasion; conventional decorum; ceremonial code of polite society.
I'm not shy about heated debate or passionate discourse, but when people get crazy or rude, that's a buzz kill. There's got to be a better code of conduct, some basic etiquette. Mos Def
Say 'Toronto' or 'Ontario,' and the immediate thought associations are with a somewhat blander version of North America: a United States with a welfare regime and a more polite street etiquette, and the additionally reassuring visage of Queen Elizabeth on the currency. Christopher Hitchens
Etiquette is all human social behavior. If you're a hermit on a mountain, you don't have to worry about etiquette; if somebody comes up the mountain, then you've got a problem. It matters because we want to live in reasonably harmonious communities. Judith Martin
Nothing is less important than which fork you use. Etiquette is the science of living. It embraces everything. It is ethics. It is honor. Emily Post
I make a distinction between manners and etiquette - manners as the principles, which are eternal and universal, etiquette as the particular rules which are arbitrary and different in different times, different situations, different cultures. Judith Martin