What is invalid definition?

An invalid definition is a definition that either does not accurately describe the term being defined or is not based on accepted conventions and principles of language and logic. Such a definition may be arbitrary, circular, vague, ambiguous, or contradictory. An arbitrary definition is one that is purely subjective and lacks any objective basis, while a circular definition merely repeats the term being defined or uses synonymous terms in the definition. A vague definition is one that is imprecise and unclear, while an ambiguous definition can be interpreted in more than one way. A contradictory definition is one that is self-contradictory or is incompatible with other definitions or principles. Invalid definitions can lead to confusion, misunderstanding, logical fallacies, and errors in communication or reasoning. Therefore, it is important to use valid definitions that are clear, precise, accurate, consistent, and coherent.