What is the term or concept for giving something a name that sounds like what it is?

[RFLS]

I'm not talking about onomatopoeia, or something as direct as a charactonym. It's also not nominative determinism, which is the opposite concept - something or someone grows into a name that is relevant. What I'm talking about is when, generally with a character, you can either make a guess as to their nature just based on how the name sounds, or, at least after the fact, it's very fitting.

For instance, Terry Pratchett was gifted with this. You wouldn't expect Sam Vimes to be a dullard. Ventinari sounds like someone with a Machiavellian bent. Nobby Nobbs sounds like, well, a walking disease. Colon...actually that might be a charactonym.

It's something that most of my favorite authors/screenwriters/etc are good at, and something I struggle with, so I'm hoping that I can find some essays or something similar to learn from about it.

[Wraith]

Aptronym - a personal name which is aptly or peculiarly suited to its owner, though not directly specifying an immediate link.

Alternatively, it could be an ideophone - a sound which evokes an idea or impression, rather than an action. They tend to be less literal than aptonyms and evoke something less tangeable.

Nominal determinism would be a Mr. Butcher working in an abattoir.
Aptronym would be Mr. Ball who works as a rugby player.
Ideophone would be, as you said, Lord Vetinari being regarded as intelligent and devious as his name makes you think of Machiavellian writings.

[Pelle]

Stereotypes?

[Lorsa]

I don't think it's an easy fix for this.

Basically, you have to use your intuition. When you say the name, what emotions does it evoke? When you think of the character, what emotions does THAT evoke? When those align, you are good to go!

Most of the time, multiple names can fit, but you'll find some that definitely do not.

Best you can do is to practice! Come up with 10 characters, explain them to us and name them. See if we agree with your chosen names!

[hamishspence]

Meaningful Name in general has this:

http://tvtropes.org/pmwiki/pmwiki.php/Main/MeaningfulName

In Making Money, Terry Pratchett has fun with this "While some Huberts are tall and thin, this was a proper Hubert - short and a bit plump, redheaded..."

EDIT: Apparently the red hair isn't typical, but the "short and plump" is:

http://tvtropes.org/pmwiki/pmwiki.php/Main/AstonishinglyAppropriateAppearance