Although biology is the study of life, even biologists don't agree on what 'life' actually is. While scientists have proposed hundreds of ways to define it, none have been widely accepted. And for the general public, a dictionary won't help because definitions will use terms like organisms or animals and plants -- synonyms or examples of life -- which sends you round in circles.
Instead of defining the word, textbooks will describe life with a list of half a dozen features based on what it has or what it does. For what life has, one feature is the cell, a compartment to contain biochemical processes. Cells are often listed because of the influential cell theory developed in 1837-1838, which states that all living things are composed of cells, and the cell is the basic unit of life. From single-celled bacteria to the trillions of cells that make up a human body, it does seem as though all life has compartments.
A list of features will also mention what life does -- processes like growth, reproduction, ability to adapt and metabolism (chemical reactions whose energy drives biological activity). Such views are echoed by experts such as biochemist Daniel Koshland, who listed his seven pillars of life as program, improvization, compartmentalization, energy, regeneration, adaptability and seclusion.To read more, click here.