Life expectancies refer to the amount of time an individual is expected to live. There are several synonyms for this term and they include lifespan, longevity, life duration, life span, mortality rate, or survival rate. Lifespan refers to the entire duration of an individual's life, while longevity is the length of time someone lives until their death. Life duration, on the other hand, is the amount of time an individual spends alive. Life span refers to the length of time someone lives from birth until death, while mortality rate refers to the likelihood of death in a specific group. Finally, survival rate refers to the number of individuals who survive a specific period of time.