The Collaborative International Dictionary of English v.0.48:

Etiquette \Et"i*quette`\, n. [F. prop., a little piece of paper,
   or a mark or title, affixed to a bag or bundle, expressing
   its contents, a label, ticket, OF.estiquete, of German
   origin; cf. LG. stikke peg, pin, tack, stikken to stick, G.
   stecken. See Stick, and cf. Ticket.]
   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.
   [1913 Webster]

         The pompous etiquette to the court of Louis the
         Fourteenth.                              --Prescott.
   [1913 Webster]

WordNet (r) 3.0 (2006):

etiquette
    n 1: rules governing socially acceptable behavior