Philistine, airtight, ballproof, beyond reach, bombproof, bulletproof, burglarproof, callous, calloused, case-hardened, closed forever to, closed to, corrosionproof, dampproof, fire-resisting, fireproof, flameproof, flinty, foolproof, hard, hardened, hardhearted, hermetic, holeproof, impassable, impenetrable, impermeable, impersuadable, impersuasible, impervious to, inaccessible, indurated, inflexible, insensitive, inured, leakproof, lost to, noiseproof, nonpuncturable, obstinate, out of reach, pachydermatous, proof, proof against, punctureproof, resistant, rustproof, shatterproof, shellproof, soundproof, steeled against, steely, stony, thick-skinned, tight, un-come-at-able, unaccessible, unamenable, unapproachable, unattainable, unavailable, undiscoverable, ungettable, unimpressionable, uninfluenceable, unmovable, unobtainable, unpassable, unperforable, unpersuadable, unpierceable, unpliable, unprocurable, unreachable, unreceptive, unresponsive, unsecurable, unsuggestible, unsusceptible, unswayable, unyielding, watertight, weatherproof