When you ask the scientists to define death, they will say “it’s just a pure chain reaction which results ultimately in the heart stopping or the brain dying”. They now refer to something called biological death. The scientists say , “we can consider people as dead when the electrical activity in the brain stops, or ceases. When this electrical activity stops, we presume that the consciousness has also ceased to exist.” According to what they have found in research, even if the breath or Heart beat stops, we can revive them - scientists refer this state as clinical death.
When we refer religion, there is aplenty of definitions present. Right from the Vedas, the Geetha, bible , Quran, all the scriptures talk vividly about death. The Hindu scriptures talk about death in an astonishingly similar way of the scientists say. The scriptures proclaim that when a person dies, it’s just like what the scientists call a biological death. The physical death, to be precise. It’s only the body which dies, and the ‘Atma’, or the self, which is the root meaning, doesn’t die. It simply goes to another body.
Krishna teaches Arjuna that when someone dies, it’s like a person changing his dress. He drops his old dress and acquires a new one. Likewise, the Atma drops a body and gets a new one. How fascinating! A totally different meaning, which gives death a new angle.
So, death holds various definitions. Add to it the belief of a "death god" in almost all the religions; The thought of which gives goosebumps, and immediately brings the image of a dark black figure, with twinking eyes , standing in the dark, and slowly walking towards us (atleast, that's what is coming to my mind !).
I’ve experienced this many a times. Once, during a certain phase, 7 people died in 5 years in my home. I saw most of the family members die, including my most favorite cousin brother. Every time we perform the yearly rituals, already the next person had gone, and the next year, the other person and so on. It was one of my life’s most unforgettable (In the other sense) moments.
There are a lot of things that scare people away, and I bet the ultimate thing is death! The only entity which has no solutions given, and which stands like a colossus in the passage of time, unconquered and unimaginable!