I. noun
1. : something belonging to or characteristic of an earlier period
2. : a style of type resembling an 18th century design of William Caslon and distinguished by graceful irregularity among individual letters, slanted ascender serifs, and but slight contrast between light and heavy strokes — contrasted with modern
II. adjective
Usage: usually capitalized O&S
: using or according to the Julian calendar — abbr. O.S.