You searched for: “propriety”
decorum, propriety
decorum (di KOHR uhm) (noun)
Good taste and behavior in both appearance and personal conduct: Elena was the epitome of decorum in all her business undertakings.
propriety (pruh PRIGH i tee) (noun)
That which is socially acceptable in terms of manners, conduct, and manner of speaking: Randal's behavior would not offend the propriety of the professional organization to which he hoped to belong.

Proper decorum when attending a wedding is expected because there are certain social rules that must be observed and so we should act with propriety.

This entry is located in the following unit: Confusing Words Clarified: Group D; Homonyms, Homophones, Homographs, Synonyms, Polysemes, etc. + (page 2)