terminology - What does NOM stand for in a datasheet and what does it mean?

The question is in reference to: http://www.ti.com/lit/ds/symlink/sn74ls00.pdf

Answer

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.