An acronym for the definition of life, used in elementary biology. It stands for

M - Movement
E - Excretion
R - Respiration
R - Reproduction
I - Irritability
N - Nutrition
G - Growth
S - Structure

Recent discoveries, including those relating to extra-terrestrial life, require a rewrite of these conditions.

Structure - an organized pattern
Reproduction - the ability to replicate and pass on instructions
Metabolism - the ability to convert energy to different forms
Growth - the ability to change structure
Evolution - the ability to change to a new entity
Irritability - the ability to interact with surroundings
Resilience - resistance to changes in the environment

For an entity to be considered alive, it must display all of these properties.