Death means--"the end of life".
Life means--"the period between birth and death, or the state of being alive".
An object which manifested must certainly have destruction. A manifested thing will certainly exist up to a certain period. If we can find or imagine the end of that period we usually denote it by the term--'death' and the period till its death is denoted by the term--'life'. Most often we are compelled to use these two terms in connection with living things. Also, we use 'live' as the opposite of 'die'. And we know that live and die are closely related to life and death respectively. Even if we think that way also, we can't imagine one without the other.
But when we use the term--'life' to mention the life of machinery, we often do not use the term 'death' to mention their 'end of life'. Even if there is a possibility of functioning of a machine, we say often "The machine is dead." when it is not functioning (for a short period). I mentioned this just to indicate that the term 'life' is sometimes used to indicate the functioning of something. Here we needn't use the term dead to define life. So, very rarely this is possible. But still there is a possibility of another question: "Would we use use the term,--'life' (of the machine) even though we hadn't the knowledge about 'death' (of something or some being). The answer still is..."No."
Some ideas become meaningful only when there is something just opposite to that idea. Eg. Day & Night. We wouldn't use the word 'night' if we hadn't the knowledge about 'day'. Similarly, the term, 'death' would have no meaning if the thing hadn't shown any sign of life or the thing was not personified. Similarly, 'life' would have no meaning if we hadn't known/thought about the end of that thing. So, a cyclic definition is often necessary to define them. (Even scientists often think about the life and death of 'lifeless' stars.)
Birth, Life and Death are the three terms to be dealt here. Both Birth and Life often imply dynamism...and Death, its end. So, Birth & Death and Life & Death can be used to define each other. Even though the term Birth is being used as the opposite of Death (and are replaceable grammatically) , we cannot use Birth & Life as we use Life & Death. I have mentioned the reason already. Also, the word 'Birth' never indicates whether the thing that manifested has got life or not. Often it is only when we use Life, it shows dynamism. So, cyclic definitions are necessary to define Life and Death.