insisted upon (verb) challenge: dispute, question
Sinonime: closed to, hermetic,
immune, impassable,
impassive, impenetrable, impermeable, imperviable, inaccessible, invulnerable,
resistant, sealed,
tight,
unaffected, unapproachable, unmoved, unpierceable, unreceptive, watertight
Antonime: exposed,
open, penetrable,
responsive,
sensitive,
vulnerable