What do they mean by "life"?

Main Entry: 1life
Pronunciation: \ˈlīf\
Function: noun
Inflected Form(s): plural lives \ˈlīvz\
Etymology: Middle English lif, from Old English līf; akin to Old English libban to live — more at live
Date: before 12th century

1 a: the quality that distinguishes a vital and functional being from a dead body b: a principle or force that is considered to underlie the distinctive quality of animate beings c: an organismic state characterized by capacity for metabolism, growth, reaction to stimuli, and reproduction
2 a: the sequence of physical and mental experiences that make up the existence of an individual b: one or more aspects of the process of living
3: biography 1
4: spiritual existence transcending physical death
5 a: the period from birth to death b: a specific phase of earthly existence c: the period from an event until death d: a sentence of imprisonment for the remainder of a convict's life
6: a way or manner of living
7: livelihood
8: a vital or living being ; specifically : person
9: an animating and shaping force or principle
10: spirit , animation
11: the form or pattern of something existing in reality
12: the period of duration, usefulness, or popularity of something
13: the period of existence (as of a subatomic particle) — compare half-life
14: a property (as resilience or elasticity) of an inanimate substance or object resembling the animate quality of a living being
15: living beings (as of a particular kind or environment)
16 a: human activities b: animate activity and movement c: the activities of a given sphere, area, or time
17: one providing interest and vigor
18: an opportunity for continued viability
19: capitalized Christian Science : god 1b
20: something resembling animate life

It always seems as if people discussing "life" are referring to different meanings of the word. How can people argue about two different interpretations of the same word? It gets very confusing. It's like debating personhood. The "life begins at conception" crowd is always aghast that any person could deny this absolute truth. But, what do they mean? Do they mean the the quality that distinguishes a vital and functional being from a dead body? Well, what is meant by a "vital and functioning being?" Do they mean an organismic state characterized by capacity for metabolism, growth, reaction to stimuli, and reproduction? The fertilized egg does have the capacity for those things but studies done have proven that 1/3 of all embryo's fail. They certainly can't mean the sequence of physical and mental experiences that make up the existence of an individual - these things would occur after birth, right? I know that they don't mean the spiritual existence transcending physical death. Obviously they do not mean the period from birth to death. Do they mean a vital or living being (if so, we're back to the whole question of what constitutes "living"?)

I believe it is really difficult to argue an interpretation or perception. I think it is equally difficult to argue a personal belief system. I believe that each individual is capable of deciding for her or his self what these things mean to them. It would be wrong to force ones interpretation, perception or personal belief system upon the general population. Therefor I believe that is it every persons right to decide for themselves what life and/or personhood means when referencing abortion and to decide for themselves what the best moral decision would be. Now, why is that concept such a difficult one to comprehend?