in·fran·gi·ble
[inˈfranjəbəl]
ADJECTIVE
formal
unbreakable; inviolable.
“there is no infrangible genetic prescription of human behavior”
synonyms:
unbreakable · shatterproof · nonbreakable · toughened · sturdy · stout · hardwearing · heavy-duty · resistant · durable · lasting · made to last · enduring · everlasting · perennial · deathless · undying · immortal · endless · inextinguishable · imperishable · ineradicable · long-lasting · adamantine · infrangible
antonyms:
fragile · ephemeral
ORIGIN
late 16th century: from French, or from medieval Latin infrangibilis, from in- ‘not’ + frangibilis ( see frangible).
Mws R Writings 