What does "bulletproofing" mean?

The process of making something bulletproof.

Bulletproofing

Common synonyms include: armor, armor plating, armoring, ballistic protection, bolster, defensive framing.

noun, verb

noun, verb ·Rare ·Advanced level

Noun

1
The process of making something bulletproof. uncountable
2
Bulletproof material. uncountable
"The rear seat areas looked unfinished, waiting for more time to weld in more bulletproofing."

Verb

1
present participle and gerund of bulletproof form-of, gerund, participle, present

"The rear seat areas looked unfinished, waiting for more time to weld in more bulletproofing."