inviability

Inviability is the state or condition of being unable to survive, develop, or reproduce under given conditions. It is the direct negation of viability, which denotes the capacity to live and reproduce. In scientific usage, inviability is often applied to biological entities such as organisms, cells, tissues, seeds, or hybrid offspring that fail to reach a viable, functional state.

Embryological inviability refers to failure of fertilized eggs to implant or embryos to develop to a viable stage. Incompatibilities between genomes in hybrids can produce postzygotic inviability, where offspring survive poorly or are infertile.

At the cellular level, inviability describes cells or tissues that cannot maintain life under specific conditions, leading to cell death or loss of function. Viability assays measure viability and are used in research and medical contexts to determine cell survival after treatment or stress.

Agriculture and horticulture use viability to describe seeds and seedlings that can germinate and establish. Seed viability testing—such as germination tests or chemical assays like the tetrazolium chloride test—assesses the potential for successful emergence. Seeds may become non-viable due to age, storage conditions, or genetics.

In ecological and conservation contexts, viability is used to predict population persistence. Population viability analysis evaluates extinction risk under demographic and environmental factors, highlighting how inviability at the individual or reproductive level can affect populations. The concept is central to studies of development, reproduction, and evolutionary biology, as well as practical applications in medicine, agriculture, and conservation planning.