Mostly vs Predominantly

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

Mostly

Top 1,000 (very common) A2 adverb

Predominantly

Top 2,000 (common) C1 adverb

Most common: Mostly

	Mostly	Predominantly
Pronunciation	🇬🇧 /["/ˈməʊstli/"]/ 🇺🇸 /["/ˈməʊstli/"]/	🇬🇧 /["/prɪˈdɒmɪnəntli/","/prɪˈdɒmɪnətli/"]/ 🇺🇸 /["/prɪˈdɑːmɪnəntli/","/prɪˈdɑːmɪnətli/"]/
Meaning	mainly or for the most part	Mainly or mostly.
Example	The sauce is mostly cream.	She works in a predominantly male environment.
Register	Neutral	Neutral
How common	Top 1,000 (very common)	Top 2,000 (common)
CEFR level	A2	C1
Part of speech	adverb	adverb
Collocations	mostly true, mostly harmless, mostly used, mostly ignored, mostly finished	predominantly white, predominantly used, predominantly found
Antonyms	rarely, seldom, never	minimally, seldomly
Common mistakes	Using 'mostly' instead of 'most' when comparing amounts., Confusing 'mostly' with 'mostly not' to communicate disagreement., Using 'mostly' in place of 'generally' or 'usually' without appropriate context.	Confusing with 'predominant' which is an adjective., Using in informal contexts where simpler words like 'mainly' are more suitable.
Usage notes	Used to describe something that is true for the majority or the largest part. Suitable in both spoken and written contexts, but avoid using in highly technical or specialized discussions.	Use 'predominantly' to emphasize that something is mostly true in a certain context. It's suitable in both spoken and written language, especially in academic or formal settings.

See it in real clips

But... mostly we had dust.

Chernobyl › S1 E1

There was a fire. It's mostly put out.

The Wire › S1 E1

The Terrace mostly.

But... mostly we had dust.

Chernobyl › S1 E1

There was a fire. It's mostly put out.

Mostly

Frequently asked questions: Mostly vs Predominantly

What's the difference between Mostly and Predominantly?

Mostly: mainly or for the most part Predominantly: Mainly or mostly.

Which is more common: Mostly and Predominantly?

Mostly is the most common in everyday English.

Which is more advanced: Mostly and Predominantly?

Predominantly is the highest level, at C1, on the CEFR scale.

Are Mostly and Predominantly the same CEFR level?

Mostly: A2, Predominantly: C1 on the CEFR scale.

What part of speech are Mostly and Predominantly?

Mostly: adverb, Predominantly: adverb.

Can you show an example of each?

Mostly: The sauce is mostly cream. Predominantly: She works in a predominantly male environment.

Can I use Mostly and Predominantly interchangeably?

Not always. Mostly and Predominantly 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.