say it: BUUL-uht-proof
bulletproof is an adjective and verb meaning "without flaws or loopholes". It carries 3 recorded senses.
without flaws or loopholes
“an ironclad contract”
“a watertight alibi”
“a bulletproof argument”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for bulletproof come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.