Synonyms of the word

invulnerable

• adj. Incapable of being injured; not vulnerable.
• adj. Unanswerable; irrefutable.

air-tight

• adj. Alternative form of airtight.

airtight

• adj. Being impermeable to air or other gases.
• adj. (figuratively) Having no weak points or flaws.
• adj. (figuratively, of a person) Highly reserved in some matter, particularly tight-lipped or tight-fisted.

bombproof

• n. An air-raid shelter, a structure designed to give protection against air raids and bombs.
• adj. Sufficiently strong to resist the effects of a blast from a bomb.

defendable

• adj. Capable of being defended.

defensible

• adj. (of an installation etc) capable of being defended against armed attack.
• adj. (of an argument etc) capable of being justified.

entrenched

• v. simple past tense and past participle of entrench.

impregnable

• adj. (of a fortress, wall, etc., also used figuratively) Too strong to be penetrated.
• adj. Capable of being impregnated.

inviolable

• adj. Not violable; not to be infringed.
• adj. Not susceptible to violence, or of being profaned, corrupted, or dishonoured.
• adj. Incapable of being injured or invaded; indestructible.

protected

• adj. defended.
• adj. (programming, of a variable, method, etc.) Having the protected access modifier, indicating that a program…
• v. simple past tense and past participle of protect.

safe

• adj. Not in danger; free from harm's reach.
• adj. Free from risk; harmless, riskless.
• adj. Providing protection from danger; providing shelter.
• adj. (baseball) When a batter successfully reaches first base, or when a baserunner successfully advances to…
• adj. Properly secured; secure.
• adj. (used after a noun, often forming a compound) Not susceptible to a specified source of harm.
• adj. (Britain, slang) Great, cool, awesome, respectable; a term of approbation.
• adj. (slang) Lenient, usually describing a teacher that is easy-going.
• adj. Reliable.
• adj. Cautious.
• n. A box, usually made of metal, in which valuables can be locked for safekeeping.
• n. (slang) A condom.
• n. (dated) A ventilated or refrigerated chest or closet for securing provisions from noxious animals or insects.
• v. (transitive) To make something safe.

secure

• adj. Free from attack or danger; protected.
• adj. Free from the danger of theft; safe.
• adj. Free from the risk of eavesdropping, interception or discovery; secret.
• adj. Free from anxiety or doubt; unafraid.
• adj. Firm and not likely to fail; stable.
• adj. Free from the risk of financial loss; reliable.
• adj. Confident in opinion; not entertaining, or not having reason to entertain, doubt; certain; sure; commonly…
• adj. Overconfident; incautious; careless.
• v. To make safe; to relieve from apprehensions of, or exposure to, danger; to guard; to protect.
• v. To put beyond hazard of losing or of not receiving; to make certain; to assure; frequently with against…
• v. To make fast; to close or confine effectually; to render incapable of getting loose or escaping.
• v. To get possession of; to make oneself secure of; to acquire certainly.

shellproof

• adj. Resistant to shelling.

strong

• adj. Capable of producing great physical force.
• adj. Capable of withstanding great physical force.
• adj. (of water, wind, etc.) Having a lot of power.
• adj. Determined; unyielding.
• adj. Highly stimulating to the senses.
• adj. Having an offensive or intense odor or flavor.
• adj. Having a high concentration of an essential or active ingredient.
• adj. (specifically) Having a high alcoholic content.
• adj. (grammar) Inflecting in a different manner than the one called weak, such as Germanic verbs which change…
• adj. (chemistry) That completely ionizes into anions and cations in a solution.
• adj. (military) Not easily subdued or taken.
• adj. (slang, US) Impressive, good.
• adj. Having a specified number of people or units.
• adj. (of a disease or symptom) severe (very bad or intense).
• adj. (mathematics, logic) Having a wide range of logical consequences; widely applicable. (Often contrasted…
• adj. (of an argument) Convincing.
• adv. In a strong manner.

tight

• adj. Firmly held together; compact; not loose or open.
• adj. (of a space, design or arrangement) Narrow, such that it is difficult for something or someone to pass…
• adj. Well-rehearsed and accurate in execution.
• adj. (slang) Intoxicated; drunk or acting like being drunk.
• adj. (slang) Extraordinarily great or special.
• adj. (slang, British (regional)) Mean; unfair; unkind.
• adj. (obsolete) Not ragged; whole; neat; tidy.
• adj. (obsolete) Handy; adroit; brisk.
• adj. (poker) Of a player, who plays very few hands.
• adj. (poker) Using a strategy which involves playing very few hands.
• adv. Firmly, so as not to come loose easily.
• adv. Soundly.
• v. (obsolete) To tighten.

unassailable

• adj. secure against attack; impregnable.
• adj. (by extension) undeniable, incontestable or incontrovertible.

unattackable

• adj. which may not be attacked.

unconquerable

• adj. Not conquerable; indomitable.

untouchable

• adj. Not able to be touched.
• n. A criminal so adept, they cannot be arrested or convicted.
• n. A pariah.
• n. In the Indian caste system, a member of the lowest caste.
• n. An incorruptible law enforcement agent.