LLL
- Ethereum
- L3 Technologies
- LL.L
- La Leche League
- Lambda Lambda Lambda
- Landau level
- Landau, Luckman, and Lake
- Lawrence Livermore National Laboratory
- Leisure Suit Larry in the Land of the Lounge Lizards
- Lenstra–Lenstra–Lovász lattice basis reduction algorithm
- Lewis's trilemma
- Lifelong learning
- Love's Labour's Lost
- Lovász local lemma
- Low-level programming language
- Loyal Lusitanian Legion
- Lutheran Hour Ministries
- The Sea Devils