I love the word "onomatopoeia"; doesn't it sound like something little children would taunt you by saying? I have to wonder if there's a point at which onomatopoeia shades over into sound effects. As Alex mentioned a couple of days ago, words like "biff", "bam" and "pow" are more or less comic book sound effects.

"sizzle", drake's "slap" and "spatter" (or "splatter"), "cough", Lord Douche's "wau wau" (for a big dog) and "woof woof" (for a middling dog), or "yappy" (for a, well, yappy little imitation dog) are perhaps better example of the type. "meow" and "mew" are maybe more like sound effects.

And what about words like "whistle"? It doesn't sound like a whistle, but you have to purse your lips into a whistling shape in order to say it. And think of the way your larynx rumbles and vibrates when you say "fog horn", or how you have to open your mouth wide to say "cry" or "scream". "screech" actually sounds like a screech, so it would be a legitimate onomatopoeia.

And as for the magical disappearing Fox, I have one word for you: inflammable. (If you remove the prefix, the meaning changes not one iota.)
I had to look up "fructify", which turns out to mean exactly what it looks like it means.
You've reminded me of a skit that Flip Wilson used to do, in his guise as Geraldine Jones. She's working the complaint desk at a department store; a customer approaches and announces that she's disgruntled. Geraldine's response: "It is not my job to gruntle you. If you want to be gruntled, then you should go home."