inconcussible
Unshakable; — Firm; solid.
an inconcussible foundation
Unshakable; — Unwavering; steadfast.
an inconcussible conviction
Unshakable; — Unassailable; incontrovertible.
The judgment has gone forth as valid and inconcussible, in spite of assessors impugning it, who belong to the highest order of religious teachers recognized by the State.
Where it comes from
From in- (“not”) + Latin concussibilis (“that can be shaken”). See concussion.
Adapted from the Wiktionary entry inconcussible (CC BY-SA 4.0).