English Reference

Word

guardrail

US/ˈɡɑɹˌdɹeɪɫ/

UK/ɡˈɑːdɹeɪl/

Definition

n. A rule built into an AI system to stop it from doing something harmful or wrong.

n. A technical constraint designed to prevent an AI system from producing unwanted outputs or taking unsafe actions.

Examples

“Developers added guardrails to limit certain model outputs.”

“The system has guardrails that prevent unauthorized actions.”

Examples

simple

“Developers added guardrails to limit certain model outputs.”

contextual

“The system has guardrails that prevent unauthorized actions.”

Real-World Examples

“Companies attempt to prevent negative consequences by placing "guardrails" on the AI but, as the Australian government found out, that is not always enough.”
BBC News · 24 Sept 2026
“When they met face to face, was this a Reagan-Gorbachev style summit of great historical import, discussing guardrails on AI and other ways not to destroy the world?”
The Guardian · 24 Sept 2026
“Such risks include preventing users and hackers from forcing an AI tool's guardrails to fail.”
BBC News · 19 Sept 2026

Etymology

Compound of guard + rail.

Original etymology written by .

Domain

Technology

This entry

Level
B2 · Upper Intermediate
Frequency
Occasional
Updated

Scan code

englishreference.com/q/guardrail

English Reference