unconquerable
un-con-quer-a-ble
adjective
Impossible to defeat, overcome, or subdue; unable to be conquered.
"Her unconquerable spirit inspired everyone."
Thesaurus
Synonyms: insuperable, unsurmountable, insurmountable, invincible, never-say-die, unbeatable, impregnable, indomitable, unsubduable, all-victorious, inexpugnable, unvanquishable
Antonyms: conquerable