From The Collaborative International Dictionary of English v.0.48 :
Conventionality \Con*ven`tion*al"i*ty\, n.; pl.
Conventionalities.
The state of being conventional; adherence to social
formalities or usages; that which is established by
conventional use; one of the customary usages of social life.
[1913 Webster]
From WordNet (r) 3.0 (2006) :
conventionality
n 1: conformity with conventional thought and behavior
2: unoriginality as a result of being too conventional [ant:
unconventionality]
3: orthodoxy as a consequence of being conventional [syn:
conventionality, convention, conventionalism] [ant:
unconventionality]