Insuperable

insuperable \in-SOO-puh-ruh-bul\ adjective
: incapable of being surmounted, overcome, passed over, or solved

Example sentence:
The battalion's strong defensive position proved to be an insuperable obstacle for the enemy.

Did you know?
"Insuperable" first appeared in print in the 14th century, and it still means now approximately what it did then. "Insuperable" is a close synonym to "insurmountable." In Latin, "superare" means "to go over, surmount, overcome, or excel." The Latin word "insuperabilis" was formed by combining the common prefix "in-" (meaning "not" or "un-") with "superare" plus "abilis" ("able"). Hence "insuperabilis" means "unable to be surmounted, overcome, or passed over," or more simply, "insurmountable." The word "insuperabilis" was later anglicized as "insuperable." Related words such as "superable," "superably," and even "superableness" have also found a place in English.