bulletproof

adjective

bul·​let·​proof ˈbu̇-lət-ˌprüf 

also ˈbə-

1

: impenetrable to bullets

bulletproof glass

2

: not subject to correction, alteration, or modification

a bulletproof argument

3

: invincible

Synonyms of bulletproof

• invincible
• armored
• invulnerable
• impregnable
• unbeatable
• unstoppable
• insurmountable
• indomitable
• unconquerable

Examples of bulletproof in a Sentence

The car has bulletproof windows.

The police officer was wearing a bulletproof vest.

Recent Examples on the Web

Besides abstaining from booze, scientists also don’t have a bulletproof way to prevent hangovers. —Lauren J. Young, Scientific American, 17 Mar. 2026

Warsh's theory of inflation is designed to make an essentially bulletproof case for cuts in this economy, unless something changes drastically. —Matt Peterson, CNBC, 5 Mar. 2026

While the administration could theoretically attempt to use alternative trade maneuvers to replicate the tariffs, there is no guarantee such a transition would be seamless or legally bulletproof. —Tristan Bove, Fortune, 20 Feb. 2026

Yet Rubio remains powerful and relatively aloof, not bulletproof but at least wearing a little bit of Teflon. —Ross Douthat, Mercury News, 26 Dec. 2025

Word History

First Known Use

1693, in the meaning defined at sense 1

Rhymes for bulletproof

• fireproof
• waterproof
• weatherproof
• aloof
• behoof
• disproof
• flameproof
• foolproof
• greaseproof
• leakproof
• reproof
• soundproof

Kids Definition

bulletproof

adjective

bul·​let·​proof ˈbül-ət-ˌprüf 

: so made as to prevent the passing through of bullets

bulletproof glass