Synonyms of the word

unassailable

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

bulletproof

• adj. (of a material) Capable of withstanding a direct shot by a bullet fired from a gun.
• adj. (idiomatic) reliable, infallible, sturdy or error-tolerant.
• adj. (usually of an idea or concept) Unbreakable, very tough.
• v. To make proof against bullets.
• v. (slang) to make resistant to failure.

impregnable

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

incontestable

• adj. Not contestable; indisputable; certain; incontrovertible.

incontestible

• adj. Alternative spelling of incontestable.

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.

invulnerable

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

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.

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.

unattackable

• adj. which may not be attacked.

unshakable

• adj. Not able to be shaken; firm, solid.
• adj. resolute, unfaltering, unwavering.
• adj. (figuratively) Having no errors or loopholes; unassailable.

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.

watertight

• adj. So tightly made that water cannot enter or escape.
• adj. So devised or planned as to be impossible to defeat, evade or nullify.