What does the
vout stand for? And is it an instance of a more general naming scheme?
The original Satoshi codebase used a programming style called "Hungarian notation", where variable names are prefixed with letters that indicate the data type they contain.
v in particular stands for "vector". So
vout just mean "in vector" and "out vector", and were (and are) the variable names for the inputs and outputs of a transaction.
In UTXOs, that name sort of got inherited, and "vout index" got abbreviated to vout in certain context.