- unconquerable - not capable of being conquered or vanquished or overcome; "a tribute to his courage...and his unconquerable will"- R.E.Danielson; "faced unconquerable difficulties"
Antonyms: conquerable, beatable, vanquishable, vincible, expugnable, stormable, subduable, subjugable
- insuperable, unconquerable - incapable of being surmounted or excelled; "insuperable odds"; "insuperable heroes"
Antonym: surmountable (indirect, via insurmountable)