The word phonology (as in the phonology of English) can also refer to the phonological system (sound system) of a given language. This is one of the fundamental systems which a language is considered to comprise, like its syntax and its vocabulary.
What sort of language system is phonology?
fundamental

Another action in 1917 that is of note was the armistice signed between Russia and the Central Powers at Brest-Litovsk. As a condition for peace, the treaty by the Central Powers conceded huge portions of the former Russian Empire to Imperial Germany and the Ottoman Empire, greatly upsetting nationalists and conservatives. The Bolsheviks made peace with the German Empire and the Central Powers, as they had promised the Russian people prior to the Revolution. Vladimir Lenin's decision has been attributed to his sponsorship by the foreign office of Wilhelm II, German Emperor, offered by the latter in hopes that with a revolution, Russia would withdraw from World War I. This suspicion was bolstered by the German Foreign Ministry's sponsorship of Lenin's return to Petrograd. The Western Allies expressed their dismay at the Bolsheviks, upset at:
Who did the Bolsheviks make peace with?
the German Empire

Lilius's proposals had two components. Firstly, he proposed a correction to the length of the year. The mean tropical year is 365.24219 days long. As the average length of a Julian year is 365.25 days, the Julian year is almost 11 minutes longer than the mean tropical year. The discrepancy results in a drift of about three days every 400 years. Lilius's proposal resulted in an average year of 365.2425 days (see Accuracy). At the time of Gregory's reform there had already been a drift of 10 days since the Council of Nicaea, resulting in the vernal equinox falling on 10 or 11 March instead of the ecclesiastically fixed date of 21 March, and if unreformed it would drift further. Lilius proposed that the 10-day drift should be corrected by deleting the Julian leap day on each of its ten occurrences over a period of forty years, thereby providing for a gradual return of the equinox to 21 March.
How much difference does the extra 11 minutes make over 400 years time?
three days