Thank you Dear vil. and you're right ı was researchin about the words before your helping,found some of them like that ;
1-pop off (Informal)
2-give up the ghost(an informal expression)
3-decease(a legal term)
4-depart this life(__formal___)
5-bite the dust(__slang idiom__)
6-breathe one's last(_informal____)
7-To kick the bucket(__slang idiom___)
8-turn up one's toes(__slang__)
9-meet one's endmaker(__slang__)
10-expire(__slang____)
11-pass away(_slang___)
12-buy the farm (slang)
13-nick the chopper (slang)
14-cash in one's chips( Slang)