- Biology. the continuous sequence of changes undergone by an organism from one primary form, as a gamete, to the development of the same form again.
- a series of stages, as childhood and middle age, that characterize the course of existence of an individual, group, or culture.
- any similar series of stages: the life cycle of a manufactured product.
- the series of changes occurring in an animal or plant between one development stage and the identical stage in the next generation
- The characteristic course of developmental changes through which an organism passes from its inception as a fertilized zygote to its mature state, during which another zygote may be produced.
- A progression through a series of differing stages of development.
- The series of changes in the growth and development of an organism from its beginning as an independent life form to its mature state in which offspring are produced. In simple organisms, such as bacteria, the life cycle begins when an organism is produced by fission and ends when that organism in turn divides into two new ones. In organisms that reproduce sexually, the life cycle may be thought of as beginning with the fusion of reproductive cells to form a new organism. The cycle ends when that organism produces its own reproductive cells, which then begin the cycle again by undergoing fusion with other reproductive cells. The life cycles of plants, algae, and many protists often involve an alternation between a generation of organisms that reproduces sexually and another that reproduces asexually. See more at alternation of generations.