Synonyms of impenetrable

1 Syllable

greek, hard, firm, firms, dun, thick

2 Syllables

firmest, proofer, delphic, muddied, firmer, close, airtight, gloppy, pathless, compact, solid, duner, unseen, murkier, harder, murky, densest, denser, hardest, jellied, trackless, sealed, mystic

3 Syllables

mystifying, perplexing, curtained, arcane, appressed, nubilous, opaque, substantial, daedalean, mysterious, fine-grained, nonporous, hermetic, compacting, telestic, impervious, fathomless, sphinxlike, unsolved, close-knit, vitrified, bulletproof, obscurer, padlocked, hard-bitten, hard-handed, hardened

4 Syllables

unknowable, inscrutable, ungraspable, nontranslucent, nontransparent, convoluted, imperviable, unpierceable, alchemistic, close-grained, impermeable, insoluble, nonrational, unpiercable, impregnable, poker-faced, inviolable, impassable, unconcluded

5 Syllables

unaccountable, incognizable, incompressible, astrological, enigmatical, irresolvable, invulnerable, indivisible, supernatural, supersensible

6 Syllables

uncomprehensible, unintelligible, undiscoverable, incomprehensible