The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
yr-
DEFINITION:
Year, season. Contracted from *ye1r-.1. Suffixed basic form *yr-o-.a.year, from Old English gar, year; b.Yahrzeit, from Old High German jr, year. Both a and b from Germanic *jram, year. 2. Suffixed o-grade form *yr--.horary, hour; horologe, horology, horoscope, from Greek hr, season. (In Pokorny 1. ei- 293.)