Meaning of the word "red line" in English

What does "red line" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

red line

US /ˈred laɪn/
UK /ˈred laɪn/
"red line" picture

Noun

a limit that must not be exceeded

Example:
Crossing that red line will have serious consequences.
The company drew a red line on budget increases.