The word "内蒙" is formed as an abbreviation of the full name "内蒙古" (Inner Mongolia). It combines the first character "内" (nèi), meaning "inner", from "内蒙古", with the first character "蒙" (méng), which is a shortened reference to "蒙古" (Měnggǔ), meaning Mongolia. This creates a concise, two-character term that retains the core meaning of the original phrase.