a Jewish holiday, the Feast of Weeks, or Pentecost, originally celebrating the spring harvest, now chiefly commemorating the revelation of the Law at Mount Sinai: celebrated on the 6th & 7th days of Sivan
See Shavuot in American Heritage Dictionary 4
also Sha·bu·oth(shə-vo͞oˈōtˌ, -əs, shäˌvo͞o-ôtˈ)
noun Judaism
A feast held on the sixth and seventh days of Sivan in commemoration of the revelation of the Law on Mount Sinai and the celebration of the wheat festival in ancient times. Also called Pentecost.