nonattainable

Nonattainable is an adjective describing something that cannot be attained or achieved. The word is formed from the prefix non- plus attainable, meaning capable of being reached. It is used in general language and in technical contexts to denote impossibility within a given framework.

In everyday use, nonattainable describes goals, standards, or outcomes that are not reachable under current conditions, constraints, or knowledge. Examples include nonattainable aspirations, nonattainable deadlines, or expectations that exceed available resources.

In scientific and mathematical contexts, nonattainable can refer to states or values that cannot be exactly realized under a prescribed model or process. For instance, in optimization, the true optimum may be nonattainable when variables are discrete, resources are limited, or the model is an approximation. In control theory or dynamical systems, a target state might be nonattainable from a given initial condition. In ethics and philosophy, some ideals are described as nonattainable given human limitations or social constraints.

Related terms include unattainable and unachievable; the choice of term can reflect emphasis on impossibility within a system (nonattainable) versus general impossibility (unattainable). Nonattainable thus conveys a bound or limitation that arises from the specific context or framework being considered.