- length of circumference
- length of iteration
- length of normal
- length of tangent
- length of the period
- length-preserving embedding
- length-preserving mapping
- length-preserving transformation
- length-variable code
- length-volume principle
- lens
- lens space
- Leo
- Leob, P.A.
- Leodamas of Thasos
- Leonardo da Vinci(即Da Vinci, L.)
- Leontief model
- Leontief system
- Leontief, W.
- Leont’ev, A.F.(Леонтьев, А.Ф.)
- Leopoldt conjecture
- Leopoldt, H.W.
- Leo the Mathematician
- Le Paige, C.
- Le Paige theorem