Nonfeasible is a word used to describe something that cannot be done or achieved due to various constraints and limitations. Some synonyms that can be used to describe the same condition include impracticable, unworkable, undoable, infeasible, unfeasible, impossible, and implausible. All these terms convey the same meaning and are interchangeable depending on the context of use. Non-viable, unachievable, unattainable, impractical, unworkable, and unrealizable are some related terms that can also be used as synonyms for nonfeasible. In summary, various synonyms can be used to describe nonfeasible, but they all communicate the same meaning of something that cannot be achieved or done.