What is "expectation of life"

Expectation \Ex`pec*ta"tion\n. [L. expectio. exspectio: cf. F. expectation.]

1. The act or state of expecting or looking forward to an event as about to happen. ``In expectation of a guest.''
   --Tennyson.

   My soul, wait thou only upon God, for my expectation is from him.
   --Ps. lxii. 5.

2. That which is expected or looked for.

   Why our great expectation should be called The seed of woman.
   --Milton.

3. The prospect of the future; grounds upon which something excellent is expected to happen; prospect of anything good to come, esp. of property or rank.

   His magnificent expectations made him, in the opinion of the world, the best match in Europe.
   --Prescott.

   By all men's eyes a youth of expectation.
   --Otway.

4. The value of any chance (as the prospect of prize or property) which depends upon some contingent event. Expectations are computed for or against the occurrence of the event.

5. (Med.) The leaving of the disease principally to the efforts of nature to effect a cure.

   Expectation of life, the mean or average duration of the life individuals after any specified age.

   Syn: Anticipation; confidence; trust.