The plural is "hisses."
"Hisses" is also the present form of the verb "to hiss".
The plural of hiss is hisses, but it a word generally used as a verb rather than a noun.
alger hiss
The Hiss ended in 2008.
The Hiss was created in 2001.
Hiss can be either a noun or a verb.Noun: The hiss from the tape deck was very annoying.Verb: The cat tends to hiss at anyone he doesn't recognize.
Hiss
Yes, they both hiss.
Mike Hiss was born in 1941.
Yehuda Hiss was born in 1946.
Hiss was a well-respected government offical.
Alger Hiss
A hiss is a sibilant sound made by angry or frustrated animals.