The difference is small and pedantic:

“Once” means “A single time”

“Nonce” means “Used a single time”

Nonce carries extra information that something is being used.

Wikipedia claims this term dates to middle English:

Nonce is a word dating back to Middle English for something only used once or temporarily (often with the construction “for the nonce”). It descends from the construction “then anes” (“the one [purpose]”).

Nonce is used extensively in the context of cryptography to mean “used exactly one time”. Usually this refers to a random number that a server shares with a client to establish secure communications.

I agree with the person who suggested linking to Wikipedia articles.

For example, it’s not much help to learn that PCIe stands for Peripheral Component Interconnect Express, because nobody calls it that. As an outsider, now I’m wondering what a component interconnect is. It’s much more useful to link to a page that gives context about how PCIe is actually used.

Very true. I believe FPGAs are also popular for aerospace applications, since it’s cheaper to design and patch programmable hardware than to design and physically install ASICs.

Vivado is software for designing hardware on an FPGA. AMD bought out Xilinx, one of the big FPGA manufacturers, a few years back. FPGAs are basically programmable digital circuits: you configure a series of internal logic gates to represent the function of a circuit with memory, data busses, registers, gates, etc. In this fashion, an FPGA could be programmed to function like a CPU, a radio, a video encoder, or nearly any other piece of digital hardware. Very useful for hobbyists and prototyping.

The thing with FPGA software is that there are no open source alternatives. FPGAs have so many complicated blobs and signing keys and proprietary IP blocks that your only choice is to use the manufacturer’s offering.