Electronic – What does V(L) stand for in Translators

NOM = Nominal, that's the value you normally can expect, and what the device is designed to.

Note that nominal values are often not the best to calculate with. If you want to go worst case you'll have to calculate with Minimum or Maximum, depending on the parameter and the application.

Bias is another word for the operating point -- a dc voltage or current about which the instantaneous value might vary.

For example, you can say you applied a "6 V peak-peak AC signal biased at +1 V". In this case the range of the signal would be from -2 to +4 V. You can see the relationship with the everyday meaning of bias, "a tendency or inclination" (dictionary.com) in this case with the meaning that although the voltage varies, it tends to be near the operating point.

As the other answers point out, the term is often used with relation to diodes and other nonlinear components.