There is a word of plural number
A foe to peace and tranquil slumber.
Now any word you chance to take
By adding “S”, you plural make;
But if you add an “s” to this,
How strange the metamorphosis!
Plural is plural then no more
And sweet, what bitter was before.
What is the word?
Can you solve this without googling it?!
Standard Q reward for the first to answer: A virtual crunchie bar