Not negligible vs Significant

When to use each in English, with meaning, register, and examples.

Not negligible

Formal Beyond 10,000 (less common)

Significant

Top 1,000 (very common) B2 adjective

Most formal: Not negligible Most common: Significant

	Not negligible	Significant
Pronunciation	🇬🇧 //nɒt ˈnɛɡlɪdʒəbl// 🇺🇸 //nɑt ˈnɛɡlɪdʒəbl//	🇬🇧 /["/sɪɡˈnɪfɪkənt/"]/ 🇺🇸 /["/sɪɡˈnɪfɪkənt/"]/
Meaning	Not something you can ignore; important.	Important or meaning a lot.
Example	The effects of climate change are not negligible, affecting ecosystems worldwide.	The research showed a significant improvement in patient outcomes.
Register	Formal	Neutral
How common	Beyond 10,000 (less common)	Top 1,000 (very common)
CEFR level	-	B2
Part of speech		adjective
Collocations	not negligible difference, not negligible impact, not negligible risk, not negligible amount, not negligible evidence	be, prove, become, extremely, fairly, very, for, to
Antonyms	-	insignificant, trivial, minor
Common mistakes	Mixing up with 'negligible' and using it in the wrong context., Using 'not negligible' to describe minor issues., Assuming it can be used without context for clarity.	Confusing 'significant' with 'significance'., Using 'significant' as a noun instead of an adjective., Overusing 'significant' in casual speaking.
Usage notes	Use 'not negligible' when discussing facts or figures that matter significantly. It's suitable for academic, technical, or formal contexts but may sound overly complex in casual conversation.	Used in academic and formal contexts to indicate importance. Avoid in very casual conversations; instead, use simpler words like 'big' or 'important'.

See it in real clips

House Of Dragons › S1 E1

The cost of the tournament is not negligible.

Not negligible

But of all these anomalies, the most significant is this:

But what is significant is, I felt the touch of God.

But of all these anomalies, the most significant is this:

But what is significant is, I felt the touch of God.

Significant

Frequently asked questions: Not negligible vs Significant

What's the difference between Not negligible and Significant?

Not negligible: Not something you can ignore; important. Significant: Important or meaning a lot.

Which is more formal: Not negligible and Significant?

Not negligible is the most formal of these.

Which is more common: Not negligible and Significant?

Significant is the most common in everyday English.

Can you show an example of each?

Not negligible: The effects of climate change are not negligible, affecting ecosystems worldwide. Significant: The research showed a significant improvement in patient outcomes.

Can I use Not negligible and Significant interchangeably?

Not always. Not negligible and Significant are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.