General terms:

* Plasma membrane

* Cytoplasmic membrane

* Cell surface membrane

* Plasmalemma

More descriptive terms:

* Phospholipid bilayer (emphasizes its structure)

* Selective barrier (emphasizes its function)

* Fluid mosaic (emphasizes its structure and properties)

The best word to use will depend on the context. For example, "plasma membrane" is the most commonly used term, while "phospholipid bilayer" might be used when discussing the membrane's structure in detail.