These are all evocative terms.  Words tend to be either mimetic or metaphoric.  One uses sound evocatively; the other, an image.  Mimetic words can replicate sounds, in which case they are onomatopoetic, or they can use sound to replicate an action, like "press" or "push" or "pull."  Almost all words ending with "-ash" do this.  Words beginning with "st-" usually signify a lack of movement, staying or sticking to one place.  The "str-" strains to stretch away from that sticking point, which takes some strength.  The term "snicker-snack" seems more of a sound than a word having meaning on its own.  Like "chortle," it could evoke a sound while inventing a meaning. Still, it is an example of the pow-er of words.  Good that you have one that raises questions.

Gregg