o·mer·ta 
(
ō-mûr
t
ə,
ō′m
ĕr-tä
)
n. A rule or code that prohibits speaking or divulging information about certain activities, especially the activities of a criminal organization.
[Italian omertà, probably from alteration (influenced by Sicilian omu, man) of Spanish hombredad, manliness, from Spanish hombre, man; see OMBRE.]