OldStyle (uncountable)

1. (historical) TheJulian calendarsystem, especially with reference toRussia, where it continued to be used until the early 20th century.
   • 1891,Thomas Hardy,Tess of the d'Urbervilles, volume 1, London: James R. Osgood, McIlvaine and Co., page16:

     The banded ones were all dressed in white gowns — a gay survival fromOld Style days, when cheerfulness and May-time were synonyms — days before the habit of taking long views had reduced emotions to a monotonous average.

   • 1911, James George Frazer,The Golden Bough, volume10, page244:

     As the [Manx] people reckon this festival according to theOld Style, Hollantide in the Isle of Man is our twelfth of November.

2. (historical) A dating system in which March 25 is theNew Year's Day.

• New Style