Definition of "bulletproof" []

• Impenetrable by bullets. (adjective)
• Informal Impervious to assault, damage, or failure; guaranteed: a bulletproof method; bulletproof arguments. (adjective)
• To make impenetrable by bullets. (verb-transitive)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Athletes arrived at the opening ceremony in bulletproof vans."
• "The silk could also have applications in bulletproof vests and improved car airbags."
• "If you sent Peter and Jane there to fly a kite, you'd kit them out in bulletproof vests first."