This study highlighted the problem that “natmal,” a synonym for “word,” is used as a flexible linguistic unit in elementary grammar education, and revealed the cause. Accordingly, analysis of the usage of “natmal” in the elementary Korean textbooks revised in 2015 revealed cases where “natmal” was used differently from the range of the word as it referred to “phrase composition” or “noun+participle”. This could be attributed to the exclusion of grammatical terms such as “phrase” and “each part of a sentence” in elementary Korean textbooks, the use of “natmal” familiar to learners, and the failure to examine the textbook’s description in detail. However, “natmal” and “word” are terms that have the same grammatical meaning and role, and should be used consistently. Because problems may occur not only in the descriptive consistency aspect of elementary language textbooks but also in cooperation with secondary grammar education.