riddle me this

United States
June 8, 2007 8:26am CST
Give me a word that starts out singular and you add an 's' at the end to make it plural but when you add another 's' its singular again. there is only 3 words you can do this to. Can you name all three?
2 responses
• United States
12 Sep 07
Thats really a good riddle... I'll have to come back with an answer.
• India
9 Jun 07
No dear I have no idea.But I want to know what this words.Please tell me.I know it can increaase my knowledge.