Over the past two decades the use of the word domain has attained wide acceptance in the military lexicon. Vague when described in doctrine, it exerts a strong influence by establishing the most basic boundaries of military functional identities. Despite the unquestioned usage of domain-centric terminology, the exact meaning of domain remains largely undefined without consideration of etymological origins. However, the word contains some built-in assumptions regarding how we view warfare that can limit our thinking. An ambiguous categorization of separate operating domains in warfare could actually pose an intractable conceptual threat to an integrated joint force, which is ironically the stated purpose of multi-domain battle.