Life  n. (pl. Lives) 1 capacity for growth, functional activity, and continual change until death. 2 living things and their activity (insect life; is there life on mars?). 3 a period during which life lasts, or the period from birth to the present time or from the present time to death (have done it all my life; will regret it all my life). B duration of a thing's existence or ability to function. 4 a person's state of existence as a living individual (sacrificed their lives). B living person (many lives were lost). 5 a individual's actions or fortunes; manner of existence (start a new life). B particular aspect of this (private life). 6 business and pleasures of the world (in paris you really see life). 7 energy, liveliness (full of life). 8 biography. 9 colloq. = *life sentence.  for dear (or one's) life as if or in order to escape death. For life for the rest of one's life. Not on your life colloq. Most certainly not. [old english]