| Main Entry: | |
| Part of Speech: | adjective |
| Definition: | airtight |
| Synonyms: | completely sealed, impervious, sealed, shut, tight, waterproof, watertight |
| Main Entry: | deep |
| Part of Speech: | adjective |
| Definition: | abstract, complicated in meaning |
| Synonyms: | Delphic, Orphic, Sibylline, abstruse, acute, arcane, complex, concealed, difficult, discerning, esoteric, hard to understand, heavy*, hermetic, hidden, incisive, intricate, learned, mysterious, obscure, occult, penetrating, profound, recondite, sagacious, secret, serious, wise |
| Antonyms: | frivolous, ignorant, shallow, superficial, trivial, unintelligent |
| Main Entry: | esoteric |
| Part of Speech: | adjective |
| Definition: | mysterious, obscure |
| Synonyms: | Delphic, Orphic, Sibylline, abstruse, acroamatic, arcane, cabalistic, cryptic, deep, heavy, hermetic, hidden, inner, inscrutable, mystic, mystical, occult, private, profound, recondite, secret |
| Antonyms: | common, familiar, known, obvious, public, unmysterious |
| Main Entry: | hidden |
| Part of Speech: | adjective |
| Definition: | unseen, secret |
| Synonyms: | QT, abstruse, buried, clandestine, cloaked, close, clouded, concealed, covered, covert, cryptic, dark, disguised, eclipsed, esoteric, hermetic, hermetical, imperceivable, in the dark, indiscernible, invisible, latent, masked, mysterious, mystic, mystical, obscure, occult, out of view, private, recondite, screened, secluded, sequestered, shadowy, shrouded, surreptitious, ulterior, undercover, underground, undetected, undisclosed, unexposed, unknown, unrevealed, veiled, withheld |
| Antonyms: | bare, exhibited, exposed, open, out, seen, showing, uncovered |
| Main Entry: | impenetrable |
| Part of Speech: | adjective |
| Definition: | dense |
| Synonyms: | bulletproof, close, compact, firm, hard, hermetic, impassable, impermeable, impervious, inviolable, solid, substantial, thick, unpiercable |
| Antonyms: | clear, penetrable, permeable, porous, soft, thin |
| Main Entry: | impermeable |
| Part of Speech: | adjective |
| Definition: | impenetrable |
| Synonyms: | airtight, dense, hermetic, impassable, impervious, leak-proof, nonporous, sealed, water-resistant, waterproof, watertight |
| Main Entry: | impervious |
| Part of Speech: | adjective |
| Definition: | unable to be penetrated |
| Synonyms: | closed to, hermetic, immune, impassable, impassive, impenetrable, impermeable, imperviable, inaccessible, invulnerable, resistant, sealed, tight, unaffected, unapproachable, unmoved, unpierceable, unreceptive, watertight |
| Antonyms: | exposed, open, penetrable, responsive, sensitive, vulnerable |
| Main Entry: | occult |
| Part of Speech: | adjective |
| Definition: | mysterious, secret; supernatural |
| Synonyms: | abstruse, acroamatic, arcane, cabalistic, concealed, deep, eerie, esoteric, hermetic, hidden, invisible, magic, magical, mystic, mystical, obscure, orphic, preternatural, profound, psychic, recondite, transmundane, unearthly, unknown, unrevealed, veiled, weird |
| Antonyms: | known, natural |
| Main Entry: | profound |
| Part of Speech: | adjective |
| Definition: | intellectual, thoughtful |
| Synonyms: | Orphic, abstruse, acroamatic, deep, difficult, discerning, enlightened, erudite, esoteric, heavy*, hermetic, informed, intellectual, intelligent, knowing, knowledgeable, learned, mysterious, occult, penetrating, philosophical, recondite, reflective, sagacious, sage, scholarly, secret, serious, shrewd, skilled, subtle, thorough, weighty, wise |
| Antonyms: | ignorant, stupid |