unfeasible

Unfeasible is an adjective used to describe something that cannot be done or achieved under the present constraints of time, money, technology, or other practical factors. It indicates that a plan, proposal, or goal is not viable within current conditions.

In planning, engineering, and policy discussions, unfeasible often flags approaches that cannot be pursued given budgetary limits, regulatory requirements, supply chain realities, or technical feasibility. It is distinct from the stronger term impossible, which expresses logical or physical impossibility rather than practical infeasibility.

The word is closely related to feasible, feasibility, and unfeasibility. Unfeasible typically carries a practical emphasis, whereas infeasible is sometimes favored in technical or formal contexts. Synonyms include impracticable, unworkable, and unviable; antonyms include feasible, workable, viable, and doable. The noun forms are unfeasibility or feasibility when describing the positive state of being feasible.

Etymology generally links unfeasible to feasible, which in turn traces to Latin roots associated with ease or ease of doing. In usage, unfeasible describes a state of practicality fail to achieve a goal, rather than a claim about logical possibility. Examples are common in project reviews, cost-benefit analyses, and regulatory impact assessments.