Li-Polymer (Lithium Polymer) - definition
This stands for a type of rechargeable battery which has evolved technologically from Lithium-Ion batteries.
Current lithium-polymer batteries are actually Lithium-Ion Polymer and perform similarly to Lithium-Ion batteries. The advantage however of Li-Polymer batteries is that they can be made much thinner.
Generally, they don't suffer from the so-called "memory effect" common to NiCd and NiMH batteries.