impregnable
adj.
5ME imprenable < OFr: see IN32 & PREGNABLE6
1 not capable of being captured or entered by force
2 unshakable; unyielding; firm !an impregnable belief"
impreg#na[bil4i[ty
n.
im[preg4na[bly
adv.

im[preg[na[ble2 7im preg4n! b!l8
adj.
5fol. + 3ABLE6 that can be impregnated