Glossary beginning with L

Lag B'Omer
According to tradition, the plague which killed many of Rabbi Akiba's students lifted on the 33rd day of the Omer. Thus, while the Omer is observed as a period of mourning, mourning is lifted on Lag B'Omer. It is a popular day to get married (the only one during the Omer, according to Ashkenazic practice: from that day forward, according to Sephardic and Reform practice). The holiday is traditionally celebrated with bonfires, and three-year-old boys receive their first haircut. Today, some three-year-old girls will also have their hair cut amidst celebration on Lag B'Omer.
Leah
The eldest of Lavan's daughters whom Lavan tricks Jacob into marrying instead of Rachel, the younger daughter, whom Jacob loves. Leah is fruitful and bears 6 of the 12 tribes as well as one daughter, Dinah, but the Bible records her unremitting grief at not being favored by Jacob.
Lilith
In the midrash, Lilith is imagined as Adam's first wife. Because she wanted equality, she wss ultimately banished, and God provided Adam with a more obedient wife. Lilith, according to tradition, lives on as a kind of demon, causing men to have wet-dreams and stealing infant boys from their cribs. Today, Lilith has been reclaimed by Jewish feminists as a symbol of women's equality.
Lulav
Palm frond. Also signifies 3 of the 4 species that are bound and waved together – the palm, the myrtle, and the willow, together with the etrog – on Sukkot. The lulav is said to symbolize the spine, while the myrtle's leaves symbolize eyes, the willow's leaves are lips, and the etrog is the heart.