Le·na 
(lēnə, lyĕ-)
(lēnə, lyĕ-) A river of eastern Russia rising near Lake Baikal and flowing about 4,300 km (2,670 mi) northeast and north to the Laptev Sea. Its delta is some 400 km (250 mi) wide.
- radial engine
- radial keratotomy
- radially
- radially symmetrical
- radial symmetry
- radial tire
- radial velocity
- radian
- radiance
- radiancy
- radiant
- radiant energy
- radiant flux
- radiantly
- radiate
- radiation
- radiational
- radiation oncology
- radiation pressure
- radiation sickness
- radiation therapy
- radiative
- radiative zone
- radiator
- radical