hiss vs hushing

hiss and hushing both are nouns.

Word	Noun	Adjective	Verb	Adverb
hiss	Yes	No	Yes	No
hushing	Yes	No	No	No

As nouns, hiss and hushing are synonyms defined as:

hiss and hushing: a fricative sound (especially as an expression of disapproval)

Other synonyms of hiss include fizzle, hissing, sibilation.

hiss (noun)	hushing (noun)
a cry or noise made to express displeasure or contempt	a fricative sound (especially as an expression of disapproval)
a fricative sound (especially as an expression of disapproval)

hiss (verb)	hushing (verb)
make a sharp hissing sound, as if to show disapproval
express or utter with a hiss
show displeasure, as after a performance or speech
move with a whooshing sound