unviable

Unviable is an adjective that means not capable of functioning, surviving, or developing. It is used to describe something that cannot exist or cannot succeed in its intended environment or context. The term is closely tied to the concept of viability, the ability to live, grow, or reproduce.

In biology and agriculture, unviable refers to seeds, embryos, or cells that fail to develop or persist. Seed viability tests measure the proportion of seeds that are capable of germinating under standard conditions; unviable seeds fail to germinate. In embryology and obstetrics, the term may describe a fetus or embryo that cannot survive to birth or in the early postnatal period, and it is used alongside nonviable pregnancies to indicate limited or absent prospects for life.

In business, technology, or project planning, an endeavor may be described as unviable when it is not economically feasible or technically achievable. Assessments of viability consider factors such as cost, market demand, competition, regulatory constraints, and technical risk.

Etymology: the word derives from viability, from Latin viabilis “able to live,” with the prefix un- marking negation. Unviable is often used interchangeably with nonviable or inviable, though preferences vary by field and region.