What does CVN mean for a US Navy ship?

Answer 1

Is is an acronym that means:

C = Carrier

V = Vessel

N = Nuclear

Actually, it's not technically an acronym. The U.S. navy assigns letter designations to different types of ships, which nominally have some reference to the description of that class, but they're not acronyms. Prefix and suffix letters are then added which indicate special characteristics - e.g. the suffix "G" usually means "Guided Missile", while the suffix "N" refers to nuclear propulsion, with the prefix "X" being assigned to experimental or prototype vessels.

For example, the U.S. Navy designation for Destroyers is "DD", while the old system used two different designations for Cruiser: CA (nominally from "Cruiser, Armored") for Heavy Cruiser, and CL (nominally, "Cruiser, Light").

So, "CVN" indicates an aircraft carrier (designation "CV") that has nuclear propulsion (suffix "N").

Note that the U.S. Navy has changed the designation system several times in the past 150 years, so the exact meaning of a designation depends on the time period when the ship was in use (as, a ship may change designation several times over its career).