Consider the following example sentence:
Sound is a form of energy that travels in all directions.
How to do you say "in all directions" (which is shown as bold in example sentence) in a single word? There's even shorter than that (all around):
Sound is a form of energy that travels all around.
I have a single word "round" [adverb]:
Sound is a form of energy that travels round.
... which doesn't satisfy me at all, as it denotes a circular motion:
ADVERB 1. so as to rotate or cause rotation; with circular motion.