Nines, in the context of the clue "Most of 1999," is likely referring to the numbers nine (9). It could be interpreted as referring to the last year of the 20th century, 1999, as the majority of the year falls under the number 9. The word "nines" itself can also refer to the plural form of the number nine, but without further context, it is unclear which specific meaning is intended.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Most of 1999. Explanations are generated by AI and may be inaccurate.