Shavuot
"Shavuot" is Hebrew for "weeks". This is one of the main annual holidays, and it symbolizes spiritual enlightenment. It is conceived as the 50'th step of the ladder, which each of us starts ascending after "Pesakh" ("Passover") - one step per day. After Passover we are supposed to elevate in our consciousness to "supreme revelation". Meaning of Christian Lent is very similar to this concept.