The word "sur-mountings" does not directly have antonyms as it is a specific noun referring to the process of overcoming obstacles or challenges. However, some possible antonyms for the concept of surmounting could be "succumbing," "yielding," "failing," "retreating," or "surrendering." These words imply defeat, giving up, or being overcome by the obstacle or challenge, which is the opposite of surmounting. In contrast, synonyms for surmounting would include "overcoming," "conquering," "prevailing," "triumphing," or "mastering," all of which suggest successfully navigating the obstacle or challenge.