Synonyms of the word

unsurmountable

• adj. insurmountable.

impassable

• adj. (of a route, terrain, etc.) Incapable of being passed over, crossed, or negotiated.
• adj. (of an obstacle) Incapable of being overcome or surmounted.
• adj. (of currency) Not useable as legal tender.

impossible

• adj. Not possible; not able to be done or happen.
• adj. (colloquial, of a person) Very difficult to deal with.
• adj. (mathematics, dated) imaginary.
• n. (obsolete) an impossibility.

insuperable

• adj. Impossible to achieve or overcome or be negotiated.
• adj. Overwhelming or insurmountable.

insurmountable

• adj. Incapable of being passed over, surmounted, or overcome; insuperable;.

unclimbable

• adj. Not able to be climbed.

unconquerable

• adj. Not conquerable; indomitable.

unpassable

• adj. Not able to be passed.