Nundinium, a Latin word derived from the word nundinum signifying the cycle of days observed by the Romans, which came to be used under the Empire to indicate a period of consulship. When, under the Empire, several pairs of consuls were created in one year, the period of a single consulship was called a nundinium.
This article incorporates text from a publication now in the public domain: Smith, William (1870). "Nundinum". In Smith, William. Dictionary of Greek and Roman Biography and Mythology.