Lag b'O·mer 
(läg bōmər, läg′ bə-ōmĕr) or Lag ba'O·mer (läg′ bə-ōmĕr)
(läg bōmər, läg′ bə-ōmĕr) or Lag ba'O·mer (läg′ bə-ōmĕr)n.
A Jewish feast celebrated on the 33rd day of the Omer (the 18th day of Iyar).
[Mishnaic Hebrew lag bā-'ōmer : lag, conventional pronunciation of lg, the number 33 when written with the Hebrew letters lamedh (having the numerical value 30) and gimel (having the numerical value 3) + bā, in the (bə, in + hā, the) + 'ōmer, the Omer; see OMER.]