Are there ANY antonyms for the word idiosyncrasy? If so, what are they?

I'm doing an essay all about the word idiosyncrasy and I need some examples of antonyms. I'll take all the help I can get. It's due tomorrow. :)

Thanks!Are there ANY antonyms for the word idiosyncrasy? If so, what are they?
Well, since idiosyncrasy means "abnormality," I'd say that "normality" would be an antonym. "Similarity" would also work in some contexts.
abnormality, accord, agreement, alikeness, concurrence, conformity, likeness, sameness, similarity, uniformity, commonality, dullness, normality, regularness, standard, uniformity, usual, usualness, strength, standardAre there ANY antonyms for the word idiosyncrasy? If so, what are they?
Yup.

Peculiarity, habit, eccentricity, quirk, foible, unconventional behaviorAre there ANY antonyms for the word idiosyncrasy? If so, what are they?
The Thesaurus does not have an antonym for the word...