Antonyms for the word "highest-ranking" include lower, junior, inferior, subordinate, lesser, and minor. These words signify a lower rank or position, contrasting with the elevated status of the term "highest-ranking." The antonyms can be applied to various contexts such as the military, organizational hierarchy, or social standing. For instance, instead of the highest-ranking officer, there can be a lower officer, or a subordinate member in a team, instead of being the top-level employee in a company. In essence, the antonyms for "highest-ranking" reflect the opposite end of the spectrum of leadership, authority, and prestige.