| Main Entry: | |
| 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: | firm |
| Part of Speech: | adjective |
| Definition: | inflexible |
| Synonyms: | close, close-grained, compact, compressed, concentrated, concrete, condensed, congealed, dense, fine-grained, hard, hardened, heavy, impenetrable, impermeable, impervious, inelastic, jelled, nonporous, refractory, rigid, set, solid, solidified, stiff, sturdy, substantial, thick, tough, unyielding |
| Antonyms: | flexible, loose, slack, soft, supple, weak, yielding |
| Main Entry: | hermetic |
| Part of Speech: | adjective |
| Definition: | airtight |
| Synonyms: | completely sealed, impervious, sealed, shut, tight, waterproof, watertight |
| 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: | impossible |
| Part of Speech: | adjective |
| Definition: | beyond the bounds of possibility |
| Synonyms: | absurd, beyond, contrary to reason, cureless, futile, hardly possible, hopeless, hundred-to-one, impassable, impervious, impracticable, impractical, inaccessible, inconceivable, inexecutable, infeasible, insurmountable, irrealizable, irreparable, no-go, no-way, no-win, not a prayer, out of the question, preposterous, too much, unachievable, unattainable, uncorrectable, unfeasible, unimaginable, unobtainable, unreasonable, unrecoverable, unthinkable, unworkable, useless, visionary, way out |
| Antonyms: | achievable, believable, obtainable, possible, reasonable, tenable |
| Main Entry: | inaccessible |
| Part of Speech: | adjective |
| Definition: | out of reach |
| Synonyms: | aloof, away, beyond, distant, elusive, far, far-off, faraway, impassable, impervious, impracticable, insurmountable, not at hand, out-of-the-way, remote, unachievable, unapproachable, unattainable, unavailable, unfeasible, ungettable, unobtainable, unreachable, unrealizable, unworkable |
| Antonyms: | accessible, approachable, reachable |
| Main Entry: | indifferent |
| Part of Speech: | adjective |
| Definition: | unfeeling, uninterested |
| Synonyms: | aloof, apathetic, blasé, callous, cold, cool, detached, diffident, disinterested, dispassionate, distant, equitable, haughty, heartless, heedless, highbrow, impartial, impervious, inattentive, listless, neutral, nonchalant, nonpartisan, objective, passionless, phlegmatic, regardless, scornful, silent, stoical, supercilious, superior, unaroused, unbiased, uncaring, uncommunicative, unconcerned, unemotional, unimpressed, uninvolved, unmoved, unprejudiced, unresponsive, unsocial, unsympathetic |
| Antonyms: | caring, compassionate, concerned, feeling, interested, involved, sympathetic |
| Main Entry: | safe |
| Part of Speech: | adjective |
| Definition: | free from harm |
| Synonyms: | buttoned up, cherished, free from danger, guarded, home-free, impervious, impregnable, in safety, intact, inviolable, invulnerable, maintained, okay*, out of danger, out of harm's way, preserved, protected, safe and sound, safeguarded, secure, sheltered, shielded, sitting pretty, snug, tended, unassailable, undamaged, under lock and key, under one's wing, unharmed, unhurt, uninjured, unmolested, unscathed, unthreatened, vindicated, watched |
| Antonyms: | exposed, unguarded, unprotected, unsafe, vulnerable |